^o^o^il Library,

I
BULLETIN

Illinois Qtate | aboratory

natural history

Urbana, Illinois.

VOLUME V.

ARTICLE XII. THE HIRUDINEA OF ILLINOIS.

By J. PERCY MOORE.

Illinois State Laboratory of Natural History

UKBANA, ILLINOIS.

February, I90I.



ERRATA.

Page 136, line 2, and jiage 182, line 17 from bottom, f(jr 'g^a read 'gj.

Page 226, line 2, page 263, line 17 from bottom, and page 267, lines

2 and 15, for 'g8, read 'g6.

Page 233, line 15 from bottom, for '82 read '82a.

Page 355, line 2 from bottom, for C. F. Hudson read C. T. Hudson.

Page 389, foot-note, for Vol. V. read Vol. IV.

Page 457, line 5, for Genera read Genus.

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Article XII.

—

The Hirudinea of Illinois. By J. Percy
Moore.

This paper is a partial descriptive catalogue of the leech

fauna of Illinois. It is founded on collections gathered from

time to time during the past twenty-five years hy the Illinois

State Laboratory under the direction of Prof. S. A. Forbes, of

which material by far the most important part, as regards

both number of species and individuals and state of preser-

vation, is that taken by Prof. Frank Smith and other mem-
bers of the staff of the Illinois Biological Station. For the

opportunity of studying this material I am indebted to the

interest and courtesy of Professors Forbes and Smith. No
doubt other species occur in this region ; indeed several

others have already been recorded from the State.

No general morphological questions are discussed herein,

though the specific descriptions include some evidence point-

ing to several generalizations of fact and theory which will

be evident to the reader. The nomenclature of somites and

annuli used, is that suggested in two recent papers (Moore
'98 and 1900). Some differences (in the enumeration of

somites of certain species) between this paper and the earlier

one just mentioned are due to the recognition of an additional

somite in the preocular lobe, as pointed out by Apathy ('88)

and Whitman ('92), and the adoption of the neuromeric

standard for the determination of somite limits as maintained

by Castle (1900) and Moore (1900). A sharp distinction has

not always been made between the different kinds of cutaneous

sense organs, unless such distinctions are readily discernible

in surface views. Eyes are described as single if they appear

so in surface views, even though sections show them to be

compound. In the figures the pigment cups alone of the eyes

are exhibited, so that in some cases they are indicated in

somites different from those which furnish their sensory

cells. In fact, with very few exceptions, the descriptions

have purposely been restricted to such features as are

479



480 Illinois State Laboratory of Natural History.

visible under a good dissecting lens, though nearly all of the

species have been sectioned and the distribution of sensillae,

etc., verified in that way. It has also been thought best to

omit full synonymical tables (partly because of the doubt

which attaches to some descriptions) and to include just

sufficient names to connect the species under consideration

with the previous descriptive literature. Blanchard's opinion

has been followed with regard to the names of European

forms. The order in which the species are considered does

not express the writer's view of their relationships; The
brief notes on habitS are the results of observations made
chiefly in the neighborhood of Philadelphia, where most of the

species occur.

GLOSSIPHONID^.

Placobdella Blanchard. '

Placobdella parasitica (Say).

Hirudo 'parasitica Say ('24).

Diagnosis.—Somites I and II are included in the preocular

lobe, which may or may not exhibit a furrow separating

them ; one pair of small pigmented eyes on the large anterior

annulus of III; the furrow Vrtl/«2 is much less distinct

than V a 2/a 3 ; cutaneous warts and papillae are numerous

but low and often inconspicuous, and the median series is

feebly developed; the epididymes and ducti ejaculatorii form

a close coil chiefly confined to somite XI.

General Description.—This tortoise leech reaches a large

size, occasionally attaining a length in extension of more

than four inches. Such huge individuals are, however, rare,

and the ordinary examples are seldom more than one half

that size. In the resting state the outline is rather broadly

oval, the anterior ends being only slightly less broadly

rounded than the posterior. The body is depressed, with

sharp margins and gently convex dorsum. When fully ex-

tended—and the capacity for extension is very great—the



The Hirudinea of Illmois. 481

body is widest near the posterior end and very slender

anteriorly. Under such circumstances the head may be

much wider than the constricted region immediately follow-

ing it and has a somewhat cordate form.

The dorsal surface is provided with numerous sensory

papilhe or cutaneous warts (PI. XLIL, Fig. 4). Except
toward the margins, where they are arranged somewhat in

two rows, they form a single series across each annulus. On
many specimens none of the papillie are at all conspicuously

elevated, and the surface may appear quite smooth ; in others

each annulus bears from ten to twenty quite large warts

which in general correspond in position with the larger warts

of P. rugosa, but have very different proportions. The median
series, so prominent in the latter, is in this species almost

obsolete. The largest and most constant are those which
overlook the dorso-lateral sensillae. In all cases they are

low, smooth, and rounded, and seldom bear more than a

single sense organ ; never a rough rosette-like aggregation at

the summit.

The shape of the head differs much according to conditions

of contraction and extension. Generally in the larger indi-

viduals it partakes of the even outline of the body and is

broadly rounded anteriorly. In the younger specimens,

especially in extension, it is somewhat expanded beyond a

neck-like constriction, and the preocular lobe is somewhat
sharply pointed. In such, also, the annuli are very clearly

differentiated, and in a few cases the preocular lobe, which
is generally simple, is distinctly subdivided into two rings

(PI. XLIL, Fig. 1).

A single pair of eyes—they are really compound— (Pl^

XLIL, Fig. 1), frequently united in a common pigment spot,

is situated on the posterior part of the second (occasionally

the third) distinct annulus. Then follow a short annulus, a
very large one, again a distinct short one, which forms the

posterior rim of the sucker below, and then two imperfectly

separated annuli V {a l-\-a 2) which completely unite ventrally

to constitute the postoral ring. On the ventral surface of

the sucker and lip most of these furrows may be readily



482 Illinois State Laboratory of Natural History.

recognized, and under some conditions are very deep. The

mouth is relatively small, and placed far forward on a median
thickening of the rim of the sucker beneath the preocular

lobe.

There is no distinct clitellum, and the gonopores have the

usual glossiphonid position of XI/XII for the male and

XII a 2/« 3 for the female. The nephridial openings, of

which there are 16 pairs, are situated on low papillae a little

anterior to the middle of the annulus a 2 on somites VIII to

XXIII.

Compared with P. rugosa the posterior sucker is relatively

large, its anterior margin reaching to XXII and the posterior

largely free. It is circular, flat, and smooth. The anus is

large and at XXVII/XXVIII.

Annuli and Somites (PI. XLII., Fig. 1).—The annulationof

this species is especially interesting and suggestive, inasmuch

as it presents the strongest kind of confirmation of the com-

parison recently made (Moore, 1900) between the biannulate

somite of Microhdella and the triannulate of the glossiphon-

ids. Even in the largest specimens, and more or less

obviously in all parts of the body, the annuli a 1 and a 2 are

evidently more closely associated than are a 2 and ad. In

young examples and toward the extremities of the body, the

neuromeric limits of the somites and the more primitive

relations of their component annuli become extremely clear.

The gradations between the biannulate and the triannulate

types are so gentle that the exact number of complete somites

cannot be definitely stated; it is impossible to decide just

where the biannulate type ends and the triannulate begins.

Of course this is more or less true of many leeches, but one

can usually rest satisfied with a decision that a particular

furrow is to be described as incipient or as complete. Not so,

however, with this species. The different values of these fur-

rows have, however, not been brought out in the plate.

I and II are preocular and are rarely separated by a recog-

nizable furrow. In some cases the furrow II/III is very

faint. At least one pair of metameric sensillae are constantly



The Hirudin ea of Illinois. 483

discernible ; the others are obscure and must be sought for

in sections.

Ill is biannulate. The first annuhis is large and generally

divided by an incipient cross-furrow, posterior to which are

the eyes and a full set of metameric sensillte. The second

annulus {a 3) is smaller, and loses its individuality at the

margins.

lY is also biannulate, the annulus (al -{- a 2) being very

large, but sometimes scarcely more visibly divided than its

preceding homologue. All of the four pairs of sensill?e except

the dorso-median are very distinct. This somite forms most
of the lateral margins of the sucker, and its posterior ring

contracts suddenly and sweeps caudad and mesiad as the

narrow posterior ventral rim of the latter.

V. When the head is expanded as described above, this

somite forms its posterior limit. The furrow a l/a 2 is more
evident than in somite IV, but a 1 and a 2 together may still

be regarded as a single large and incompletely divided

annulus. In no case does this furrow extend beyond the

margins of the body, so that the ventral surface of the

annulus is entirely undivided. The dorsal metameric sensillte

occupy the posterior constituent {a 2). The small annulus

a 3 is a trifle more than half the length of the large one, and
the furrow a 'I/a 3 is very much deeper and more distinct

than a l/« 2, though somewhat less so than V/VI ; it is also

fully developed ventrally.

VI may be provisionally and arbitrarily regarded as com-
plete, but even in this somite the furrow «l/rt' 2 is dorsally

much less obvious than a 2/a 3 and becomes on the ventral

side very faint, and in small specimens especially obsolete.

These two potential annuli are also smaller and more inti-

mately associated on the ventral than the dorsal surface.

Viewed from either above or below the marginal curvatures

of rt 1 and a 2 are more homogeneous and the emarginatious

much less deep and abrupt than between a1 and aS, thus

further indicating the closer growth relations of the former

two.

Much the same conditions prevail in succeeding somites,



484 Illinois State Lahoratori/ of Natural History.

but become gradually less and less obvious as ^ 1 becomes
relatively larger and more completely dissociated from a 2.

At the same time all of the furrows and the emarginations

become more uniform ; but in some specimens of large size

and in a great many of the smaller ones the intersomitic

furrows remain more distinct and a l/a1 less distinct for the

entire length of the body, and especially is this so on the

ventral surface. The external limits of the somites are often

quite as distinctly indicated as in Microhdella.

On the fully developed somites of the middle region a 3 is

always the largest annulus (PI. XLII., Fig. 4), but, except in

the posterior somites of large individuals, there is no indica-

tion of further subdivision into b 5 and b 6. Anteriorly, and

especially in young individuals, 0.2 is longer than a 1, but in

the middle region it is only equal to or slightly less than this.

Unlike P. rugosa this relative size of the annuli is the same
ventrally and dorsally, and the ventral furrows are either

exactly continuous with the dorsal or all are slightly and

equally in advance of them at the margins.

At the posterior end, somite XXIII is triannulate above

;

but below the furrow a 1/a 2 becomes more or less reduced.

Dorsally the marginal curvatures and emarginations present

the features described for the anterior end, and a 3 is slightly

shorter than a 1

.

XXIV. Although the annulus a 3 unites with a 2 mesially

and a 1 remains distinct for its entire width, contrary to the

relative disposition of these annuli anteriorly, the marginal

curvatures and emarginations still associate a 2 more closely

with its predecessor than with its successor. Marginally, at

least, a 1 is the largest component. On the ventral side all

three annuli unite more or less completely into one.

XXV is very incomplete ; a 1 and a 2 are inseparable

and a 3 is distinct only marginally. XXVI is still more

faintly biannulate at the margins or even entirely unian-

nulate. XXVII is uniannulate.

Reproductive Organs.—The six pairs of testes lie in the

posterior parts of somites XIII to XVIII, extending some-

what into the succeeding somite in each case. The vasa



The Hirudinea of IlUiwis. 485

deferentia are ventrad and laterad of the testes. A slightly

enlarged coiled region of the ducts in somite XI corresponds

to the epididymes and ducti ejaculatorii, which latter become
constricted befbre opening into the somewhat enlarged prostate

cornua. The latter are quite distinct from one another

except where they join beneath the nerve cord at the small

bursa. There is no true muscular atrium.

Alimentary Canal.—The protrusible pharynx is very slender

and when at rest reaches into somite X, where at its base it

receives the pair of common ducts of the pharyngeal glands.

There are two of these much lobulated glands on each side.

The larger one extends by the side of the pharynx from a

point opposite to the female pore in XII to the middle of IX.

The main duct arises in this lobe at the junction of its

anterior and middle thirds. The second gland is smaller.

Beginning in a short duct which joins the middle of the

principal one, it extends forward, dipping beneath the

pharynx, as far as the anterior end of the main gland, where

it emerges from beneath the pharynx and continues forward

a short distance. Very frequently, but apparently not invari-

ably, a median annectant lobe joins the lateral halves across

the ventral face of the pharynx.

The lateral cfeca are exceedingly well developed and their

numerous lateral divisions reach almost to the margins of the

body. Six pairs correspond very nearly to as many somites

(XIII to XVIII). Except the first, they are arranged as a series

of overlapping chevrons with the angles directed posteriorly.

A seventh much larger pair of cfeca arises in XIX and con-

tinues backward parallel with the intestine to about XXIII.

The intestine bears four pairs of long simple caeca which are

directed laterad dorsal to the last described.

Color.—Placohdella parasitica is very richly colored. On
the dorsal surface the ground color of brown, greenish brown,

or olive green is variously spotted, striped, and blotched with

bright yellow, which replaces the ground color more or less

extensively. Two specimens entirely alike can scarcely be

found, so that a description applicable to all cannot easily

be framed in a few words. The following, however, probably



486 Illinois State Laboratory of Natural History.

includes the most essential features : The preocular region

is very light colored, with a bright orange spot, sometimes

including the eyes. The light yellow areas are chiefly con-

fined to a median longitudinal stripe, to marginal spots, and

to a pair of series of spots or blotches between these two.

Sometimes the median band is continuous for the whole

length, sometimes its middle part disappears, and sometimes

small remnants of it remain at the ends only. It is of very

irregular width, alternately expanding widely at intervals of

about three somites and contracting between. The marginal

spots are generally very regular, of somewhat triangular

shape, and extend over the two annuli which lie between the

successive neural annuli, the latter being dark colored at the

margins. It is only at the ends of the body that they suffer

modification. The intermediate series are the most variable.

They may be formed of small spots including the dorso-

lateral sensillae, and occurring on the neural annuli of every

somite or only on every second or third somite ; they may
extend over a 3 as well as a 2 or they may become large

irregular blotches reduced in number and extending over

several somites ; they may coalesce more or less into irregular

longitudinal stripes which are likely to be constricted on

a, 1 ; and they may unite in various ways with the mar-

ginal spots or with the median band. The ground color

may greatly predominate or almost disappear.

Habits.—^This very common leech is found most frequently

adhering to the plastron or naked parts of the skin of

various species of turtles, to which it clings very tenaciously.

In the early spring, before and during the period of produc-

tion of spermatophores and oviposition, they feed eagerly

and gorge themselves with blood. Like other species of

similar habit they not infrequently kill their host by thus

draining its blood. At other seasons they may be kept for

months without food. Not infrequently this species is also

found on floating wood in ponds and ditches or under stones

in streams, where it feeds on small oligochsetes, etc.



The Hirudinca of Illinois. 487

Placobdella rugosa (Verrill).

Chpnine ornatd var. ruyo-sa Verrill (''74).

Diagnosis.—Somites I and II distinctly and completely sep-

arated, usually strictly uniannulate ; the single pair of eyes

very close together on the posterior part of the large annulus

of III ; the furrow Y a Xja 2 quite as distinct on the dorsal side

as V rt2/</ 3 ; cutaneous papillte numerous, mostly very large

and rough and the median series very conspicuous ; repro-

ductive organs essentially as in P. parasitica.

General Description.—Although reaching a large size the

largest individuals probably do not equal the largest of

P. parasitica. Generally the length is from one to two

inches. When resting this is the broadest and flattest of

our leeches, the whole body being excessively depressed and
foliaceous. A living individual in this state measures twenty-

two millimeters long by fourteen broad. Incapable of the

great degree of extension possible to P. parasitica it never

becomes very slender.

The integuments have a peculiar translucent appearance,

quite different from the opacity of P. parasitica. The whole

dorsal surface of the body is exceedingly rough, in large living

examples being clothed with a veritable forest of papillie from

which the eye readily picks out three longitudinal series of

more prominent ones, conspicuous not only because of their

large size but because of the regularity and constancy of their

occurrence. One of these is median, the others about half-

way to the margin. Toward the anterior end they become

smaller and fewer ; at the posterior, the median series ceases

and several very prominent papillie appear in a short series

on each side of the median line. Further details are given

below under the description of a typical somite.

Under all conditions of contraction or extension the anterior

sucker partakes of the regular curvature of the body and never

appears as an appreciably expanded disc. In preserved spec-

imens it is deeply concave, with a high but thin posterior

margin formed by IV, and thicker lateral margins. Anteriorly

the preocular lobe is rather narrow and more or less inrolled



488 Illinois State Laboratory of Natural History.

ventrally, where it is continuous with a thick rounded ridge

which extends to about the middle of the sucker and ends at

a deep curved furrow continuous laterally with III/IV. The
mouth is a minute pore placed near the anterior end of the

ridge beneath the overhanging preocular lobe, Metameric

sensillae on the preocular region have not been detected in

surface view, though they can be demonstrated readily enough
in sections. The eyes are essentially as in P. 2:)arasitica.

No clitellum has been found. The male sex pore is at XI/XII
and the female at XII a2/a3, but a 3 is enlarged mesially and

pushes forward into an emargination in a 2, so that the female

pore generally lies rather more within the latter. The male
orifice is the larger and is surrounded by more or less promi-

nent rugosities. The most anterior nephridial openings which

have been detected are on VIII, the last on XXIII.

Although of smaller size than in P. parasitica the posterior

sucker is rather large and has a longitudinal diameter slightly

exceeding the transverse. It extends anteriorly to XXIII.
The entire free dorsal surface bears papillae which are nu-

merous and rough on the posterior exposed part, where four

to six radiating rows are larger than the others. Anus
XXVII/XXVIII.

Annuli and Somites (PI. XLII., Fig 2).—I and II consti-

tute the preocular lobe.

III is biannulate, with the large anterior ring very faintly

divided by an incipient cross-furrow, posterior to which are

the closely approximated eyes, two pairs of metameric sen-

sillfe, and one pair of warts which apparently belong to the

dorso-lateral series. The second annulus bears a full set of

the characteristic papillae or warts, but they are of very small

size.

IV differs from III dorsally in that a 1 is more distinctly

differentiated from a 2 by a furrow which is always distinct

marginally but may disappear mesially. The anterior annu-
lus (a 1) thus indicated is smaller than a 2, and bears no
papillae except in the case of two exceptionally rough indi-

viduals from Tinicum Island, near Philadelphia. The a 2

constituent bears all of the dorsal sensillae except the dorse-



The Hirudinea of Illinois. 489

median and the supra-marginal, and the more characteristic

papillie belonging to this ring. ^ 3 is about half the

length of the larger double annulus, bears its characteristic

papillfie, and forms the margin of the posterior rim of the

sucker.

V is triannulate dorsally, a 2 is slightly wider than a 3, and

the latter than a 1, but all furrows are equally well developed,

until at the margin a Ija 2 suddenly disappears, leaving two

ventral annuli of approximately equal size.

Eighteen somites (VI to XXIII) are completely triannulate.

A curious feature of these (PI. XLIL, Fig. 3) is that the

relative lengths of the annuli differ dorsally and ventrally

;

above, a 2 is the largest, a 3 slightly less, and a 1 obviously

the smallest ; below, a 2 is the shortest, and a 3 just appreci-

ably shorter than a 1. This is readily explained by compari-

son of the relative positions of the furrows. Along the margins

of the body is an exceedingly thin expansion, crenulated in

correspondence to the annuli. Set in the emarginations be-

tween successive lobes are narrow wedge-shaped pieces which

in the contracted leech assume the position of more or less

vertical folds uniting the dorsal and ventral furrows. When
the leech is extended these pieces of course become horizon-

tal, and the dorsal and ventral furrows assume the following

relative positions ; a dja 1 is ventrally in advance of its dorsal

part, a l/a2 is ventrally slightly behind, and a'^/aS again

ventrally in advance. This lack of alignment characterizes

all furrows from about VI/VII to XXIV/XXV.
On the dorsal surface some very faint transverse wrinkles

pass between the principal papilla? and are about equally

apparent on all of the annuli. Ventrally a 1 and a 2 may be

more or less divided, the portions toward the ends of the

somites being the smaller ; a 2 very rarely shows faint traces

of such a division. In this feature and in the rough cutaneous

papillie the species resembles Hcementeria officinalis.

The disposition of the papillae on a typical complete somite

is shown in the figure (PI. XLIL, Fig. 3), and is as follows:

On the dorsal surface of each annulus are two rows of small

smooth sense papillae separated by the transverse wrinkles



490 Illinois State Lahoratory of Natural History.

above mentioned and differing somewhat in size and distance

apart. They are generally single but here and there are

grouped in twos, threes, or fours. The number in a transverse

row counted singly or as groups is from thirty to fifty on the

middle region of the body. A few others may be scattered

between the rows or even form a third broken row between the

larger papillae, particularly on ^ 3. Along the margins large

numbers may be aggregated. The large rough papillae are

prominent wart-like elevations of the integuments, some of

which measure more than a millimeter in height in living

examples. They appear not to contract under ordinary stim-

uli, but are sometimes very much less elevated in preserved

material. They are generally conical in shape, their summits
bearing a ring of from four to twenty smaller sense papillae

arranged around a central larger one. When the number is

greater than eight or nine they are likely to form a less regular

ring and to extend further down the sides of the wart, while the

central one becomes replaced by two or three. A relation

between the size of the wart and the number of papillae in its

crown seems to exist. Of the median series (mp) that on a 2

is the largest and often bears twice as many sense organs as

that on al, which is the smallest. The next series counting

laterad (nidp) is always represented by a very large wart on

« 3, by a much smaller, frequently absent, one on al, and
on « 2 is replaced by a rather prominent but smooth papilla

which supports the dorso-median sensilla (mcl). This cannot

be confounded with the rough papillae. The next important

series (dtp) is made up of a large one on ^ 2, a smaller one

on aS, and a very much smaller one or none on al. Just

external to the large one on aQ, is the dorso-lateral sensilla

(dl), which is somewhat elongated transversely and is litttle

elevated above the surface. At the margin are two rows

so imperfectly developed that they are probably better

described as a single irregular row (dmp) sometimes repre-

sented by two warts on a single annulus. Warts of smaller

size are generally present, but are more irregularly distrib-

uted than the fairly constant ones just described. They are

most frequent on al, where one such is likely to be present



The Hirudinea of Illinois. 491

between the median and dorso-median rows, two between

the latter and the dorso-lateral, and two between this and

the marginal. A 2 sometimes bears one internal and one

external to the dorso-median sensilla. The marginal sensillae

are small.

At the posterior end somite XXIII, though triannulate,

shows some peculiarities. The median papilla on a 2 is

much reduced in size or absent, and on each side of the

middle line appears a very large rough wart not represented

on any of the anterior somites. In surface views no trace of

the dorso-lateral sensilhie can be found, but it is suspected

that they have been raised to the top of the large warts just

described, where a truncated clear area is sometimes visible.

Annulus ^ 3 is somewhat shortened, but in all other respects

this somite is typical.

On XXIY the same features appear somewhat exaggerated
;

the papillfe are as described for 'XXIII, and annulus aS is

distinctly smaller and mesially joined to « 2.

XXV, XXYI, and XXVII show successive steps toward a

simpler condition. The first is generally divided into two

annuli nearly or quite to the middle ; the second, for a greater

or less distance from the margin ; and the third, just at the

margin or not at all. In all of these cases the anterior

annulus is the larger and bears a rather large median wart

;

the peculiar pair of warts of XXIII and XXIV is wanting

;

and the reduction in size of all other warts leads to the

relatively greater prominence of the dorso-lateral series.

Reproductive Organs.—The genital organs differ in no im-

portant respect from those of P. parasitica. The only differ-

ence apparent in a number of dissections is that the prostate

cornua of this species are rather longer.

Alimentary Canal.—Only two minor characters in which

the digestive tract of this species differs from P. jyarasitica

need be mentioned : the pharyngeal glands have no median
annectant lobe ; and the caeca are less finely and numerously
divided.

Color.—The colors of living examples of this species gener-

ally impress one as a pepper-and-salt mixture of various



492 Illinois State Laboratory of Natural History.

light and dark browns, yellows, and greens, which, owing to

the translucency of the integuments, are seldom sharply

defined. They appear to be more definite on preserved

specimens, and certain metameric features and resemblances

to the plan of coloration of P. parasitica are recognizable.

The light marginal spots are present with the same regularity

as in that species. The light median stripe may usually be

distinguished at the anterior, and less frequently at the

posterior, end. It is constricted or quite interrupted by the

dark color of the neural annuli, which encroaches on it,

while in the intervals between them the light color extends in

narrow bands more or less laterad. In the middle region of

the body short longitudinal median brown or brownish green

lines alternate with light spots. The former correspond to

the constrictions, the latter to the expansions, of the median

stripe of P. parasitica. Sometimes there is a very distinct

continuous narrow median dark brown line. The rest of the

dorsal surface is generally variegated browns, with the

papillae light yellow or green and the position of the dorso-

lateral sensillse indicated by rather large and conspicuous

light spots.

Habits.—A species of sluggish habit ; abundant in running

waters, where it is found clinging to the under sides of stones.

It also attaches itself to the under side of floating wood in

ponds and ditches. Particles of mud cling to the mucous

secretion on the body and render it inconspicuous, and the

leeches frequently bury themselves partially beneath the

sediment at the bottom. They seldom swim, but creep along

the surface to which they are attached. If thrown into the

water they roll up and sink to the bottom. They carry

the eggs or young in early spring, a habit which is common
to most members of the family.



The Hirudinea of Illinois. 493

Glossiphonia Johnson.

Glossiphonia complanata (Linn.eus) Johnson.

Hirudo comjylanata Linnreiis (1758).

Clepsine elegans Verrill ('74).

Diagnosis.—Somites I to IV each uniannulate, II and III

often imperfectly separated and IV sometimes faintly subdi-

vided ; three separate pairs of pigmented eyes in somites II,

III, and IV, the first pair commonly crossed by the furrow

II/III ; V is biannulate ; male pore at XI/XII, female pore at

XII a 2/a 3 ; dorsal cutaneous papilla? low and inconspicuous,

principally in four series, no median series ; epididymis

folded into a long loop which reaches into somite XVIII or

XIX; nine pairs of testes (XIV to XXI).

This is a species well known in Europe, of which figures

may be found in Moquin-Tandon ('46, Plate XII.), and dia-

grams of the annulation and a description in Blanchard ('96),

while Verrill describes the colors of American specimens.

It abounds in certain localities under stones in running water,

is very active but rolls itself into a ball when disturbed, and
feeds chieriy on small snails and annelids.

Glossiphonia lineata (Verrill).

Clepsine papillifera, var. linvata Verrill ('74).

? Glossiphonia triserialis E. Blanchard ('49).

? Helobdella triserialis R. Blanchard ('96).

This species is almost certainly G. triserialis, and I hesitate

to give it that name o;ily because K. Blanchard ('96) has

stated that the male pore of his specimens is situated at

23/24 (XI/XII) instead of one annulus further caudad as in'

the form here described.

Diagnosis.—Somites I and II uniannulate, III and IV bian-

nulate, and V triannulate ; the single pair of very large eyes

situated in IV; male pore at XII al/a2, female pore at XII

rt2/a 3 ; dorsal cutaneous papillae conspicuous (owing to black

color), generally in three (sometimes in five) longitudinal



494 Illinois State Laboratory of Natural History.

series, of which the median is the best developed ; epididymis

forming a loop which reaches into somite XV.

General Description.—^A small species seldom over half

an inch in length, but capable of moderate extension. In

the resting state broad and slightly convex above but not

foliaceous, the body being rather thick ; when extended,

strongly convex.

The anterior sucker is of moderate size and has a rather

thick margin into which the annulations extend. It is deeply

concave and presents no central elevation. The mouth is

large and situated just behind the anterior rim of the sucker,

apparently in somite II. Occasionally it is succeeded by a

transverse fold. The eyes, of which there is a single pair,

are of remarkable size, their diameter being nearly equal

to the length of annulus IV (a l-\-a'2) in which they lie. They

are simple and correspond to the second pair of G. complanata.

The genital pores are separated by but a single annulus, the

neural annulus of somite XII ; they consequently both lie

within the limits of that somite.

The posterior sucker is large but relatively little exposed,

elliptical in form, and with a thick margin. It reaches for-

ward to XXIII a- 2.

Annuli and Somites (PL XLIL, Fig. 6).—I and II are

uniannulate and constitute the undivided anterior lobe.

III is biannulate, the anterior ring being somewhat the

larger. No sensillae are visible in surface views, but sections

show that the eyes are derived from this somite.

IV is biannulate, but the anterior annulus is relatively larger

and is faintly subdivided ; it bears the very conspicuous pair

of eyes. At the margin this somite becomes uniannulate

and forms the posterior rim of the sucker.

y is triannulate above. ^2 is much longer than a 1,

especially mesially, where it appears to be almost subdivided.

The furrow a 2/a 3 is the deepest in this neighborhood and

defines the posterior limits of the head very sharply. Ven-

trally a 1 and a 2 unite while « 3, as usual, remains distinct.

VI is the first of the fully triannulate somites, and all three

annuli are distinct ventrally as well as dorsally. In all of the



The Hirudinea of lUinois. 495

complete somites a 2 is somewhat wider than its fellows,

dorsallj' at least, and is rendered further conspicuous owing

to the papillfe which it alone bears, its slightly protuberant

margins, and the white spots which characterize it.

The arrangement of the cutaneous papilliTC, though variable

in detail, is very characteristic of the species among local

forms. But three constant and conspicuous series exist

(PI. XLII., Fig. 6); a median (mp) and a pair of dorso-

laterals {dip) situated nearly half-way to the margins. The

median series begins sometimes as far forward as somite

YI or VII, but seldom becomes prominent before IX or X,

from which it continues to XXYI. This is really not a strictly

median series, as the papilla^ comparatively seldom lie exactly

in the median line but usually a little to the right or the left.

Yery frequently the single conical papilla is replaced by two

which are placed more or less close together, in contact or even

united into a bilobed or a transversely elongated one. The

whole appearance of the series must lead one to recognize its

dual character. All of these papillne are prominent, sharp-

pointed, simple cones, whose black color amid white or pale

surroundings renders them doubly conspicuous. They are

largest in the middle of the series and diminish toward the

ends, that on XXYI being very small and some of the

anterior ones minute.

In every important feature the dorso-lateral series is

similar to the median. The papillte begin further back and

are seldom conspicuous anterior to XIII, from which point

they continue to XXYI or XXYII, the last two or three being

small. They are somewhat smaller than the median ones

and are more likely to be absent from a somite. Though

forming a nearly perfect series anteriorly, they present an

even greater tendency toward irregularity and doubling

posteriorly.

Occasionally one or two isolated papillae are found between

the median and dorso-lateral series, and remnants of a very

imperfect supra-marginal series occur more frequently on

several of the posterior somites. Yery few and faint papillae

occur on the sucker. The dorsal surface of the body



496 Illinois State Laboratory of Natural History.

is everywhere roughened by projecting cutaneous sense

organs.

The anterior metameric sensillte (PI. XLII., Fig. 6) are very

difficult to make out in surface views, but about X or XI they

become very conspicuous and continue so to the posterior end.

Here they appear as eight dorsal series of clear white spots.

The dorso-medians (md) are placed on each side of the median
papillae, separated by a distance about two thirds of that which

intervenes between them and the dorso-laterals. The latter

(dl) are just about half-way between the mesion and the

margins, or a trifle nearer to the latter, and consequently are

external to the dorso-lateral papillae. The dorso-marginals

(dm) are well back from the margins, being about as far from

the dorso-laterals as are the dorso-medians, except on the

incomplete somites, where the former distance is less. The
supra-marginals (sm) are very minute and on the exact

margins as viewed from above, except on the incomplete

posterior somites, on which they are somewhat removed from

the margins. The ventral sensillae have not been studied.

Reproductive Organs.—In most respects resembling the

species of Placohdella the reproductive organs differ from

theirs and resemble those of G. complanata in one important

feature : the enlarged portion of the sperm-duct (epididymis

and ductus ejaculatorius), instead of simply coiling up, extends

caudad in a long straight loop which lies ventrad to the gas-

tric caeca and reaches at least as far as ganglion XV.
Alimentary Canal.—The proboscis is of relatively much

greater diameter than in the two species of Placohdella

described, and the gastric caeca are of small size and scarcely

lobed. There are but six pairs of these caeca, which increase

in size caudally, and the first of which (in XIV) is rudi-

mentary or sometimes absent. In all of these respects this

species is intermediate between G. complanata and G.

stagnalis.

Color.—The colors are here described from preserved

material. They are very simple and effective. Below, a

plain ash-color; above, the same color marked by eleven or

twelve longitudinal stripes of brown which are further com-



The Hirudinea of Illinois. 497

pounded of narrow brown lines, the number of which varies

according to the width of the stripe. The longitudinal stripes

correspond with the arrangement of the musculature as

described for other species by Graf ('99). On many speci-

mens these stripes are more or less interrupted on a 2 of each

somite by transverse whitish spots which occur almost con-

stantly in two, four, or six longitudinal series, of which the

most constant lie just external to the dorso-lateral papillae,

the next on the flanks of the median papillae, and the third

near the margins. The extreme of this arrangement results

in a handsome metameric pattern in which a 2 becomes con-

spicuously marked by a row of white spots which on the

posterior somites unite to form a band. In such specimens

the ground color becomes a pale brown marked by numerous

narrow dark brown or almost black lines, of which a pair

near the middle line are very conspicuous. The white spots

are least developed anteriorly, but become more extensive

and closer together posteriorly. Individuals differ greatly as

to the exact manner and extent of the complementary develop-

ment of light and dark elements in the pattern. The entire

predcular region is beautifully white, while brown rays on a

white ground mark the sucker.

Habits.—In habits G. lineata resembles G. complanata, with

which it is frequently found. Probably this species inhabits

colder brooks than any other of our glossiphonids.

Glossiphonia stag-nalis (LiNNiEus).

Hirudo stagnalin Linnttus (1758).

Hirudo bioculata Bevgmann (1757).

Clepsine modesta Verrill ('74).

Diagnosis.—Somites I to III included in preocular region
;

single pair of eyes on anterior annulus of IV, which is

obscurely biannulate ; V biannulate ; VI to XXIV triannu-

late ; XXV and XXVI biannulate, the latter somewhat united

to XXVII; genital orifices as in G. lineata; a dorsal chitinoid

glandular bursa situated at VIII a 1/a 2
;
gastric caeca small,

simple, variable, never more than six pairs, of which any or

all of the first three may be absent ; size small and form con-



498 Illinois State Laboratory of Natural History.

vex, capable of great extension ; no papillae nor conspicuous

markings.

This widely distributed species is figured by Moquin-Tandon

('46, PI. XIII., Fig. 16-26), and the annulation of the

anterior end by Blanchard ('96).* The species is exceedingly

abundant everywhere in the shallow waters of rivers, lakes,

and ponds, in small streams, pools, and ditches, in fact

everywhere where comparatively warm shallow fresh waters

are found. It is found clinging to the under sides of stones,

and between the ensheathing leaf stalks of aquatic plants,

fallen leaves, etc. When disturbed it creeps actively to a

place of concealment. The favorite food is small annelids

and gastropods, but blood is also taken from injured fish,

frogs, etc. The breeding season lasts all through the spring

and early summer.

HEMICLEPSIS VejdOVSKY.

Hemiclepsis carinata (Verrill).

Clepsine papillifera, var. carinata Verrill ('74).

Diagnosis.—Somites I and II rather distinctly biannulate

;

the single pair of eyes on III ; the widely expanded head

pedicellate on a wide pedicle formed by VI ; annulus a 3 of

complete somites much larger than a 1 or a 2 and unequally

subdivided at the margins ; the dorsum bears three prominent

papillated keels; the epididymis and ductus ejaculatorius

form a few simple coils in XI and XII.

General Description.—A medium-sized glossiphonid of

striking appearance. It seldom reaches a length of more

than one and one half inches when partially extended in the

act of creeping. The shape of this species is entirely char-

acteristic among known Illinois leeches. In the large size,

distinctness, free margin, and pedicellate attachment the head

resembles that of the Ichthyohdellidce. The body is more slen-

* By far the best description of this species extant has recently been published by

Castle, in Bull. Mus. Comp. Zool., XXXVI. (1900), pp. 21-33.



The Hirudinea of Illinois. 499

der and less flattened and foliaceous than in other glossiphon-

ids of equal size. It is never very wide and depressed, but on

the contrary rather strongly convex dorsally. Capable of

great extension and contraction the body may become very

slender, especially anteriorly, or short, thick, and elliptical,

and very convex above. In both states the head stands out

clearly and sharply as a distinct region. This is an excellent

character for distinction from the other leeches described

in this paper.

Viewed from above the head is very broadly cordate, the

bluntly rounded apex being anterior. Below, the very free

posterior margin is entire and slightly convex or straight.

This margin appears to be formed by the very strong down-

ward and backward development of V, which becomes much
enlarged below and whose ventral sensillae are visible on the

lateral parts of the posterior margin of the sucker. Dorsally

the surface of the head or sucker is strongly annulated. At
the margins the annuli are supplemented by a narrow but

distinct undivided rim. The ventral surface is smooth, with

sometimes two or three faint transverse furrows. .Just inside

of the anterior border is the small mouth, apparently in II,

The labial sense organs are exceptionally well developed

around the entire margin of the sucker.

The posterior limit of the head is clearly defined both above
and below by the furrow Y/YI. This is followed by two small

annuli (which are regarded as a divided YI ^1) which form
a short neck embraced anteriorly and concealed below by
Y a 3. Yentrally they become still smaller and perhaps

united. Posterior to this point the body increases rapidly in

width and the posterior part of YI is equal to lY, the widest

part of the sucker.

The most striking characteristic of the species, however,

is the presence of tlu'ee prominent carinse which extend from
just behind the head to the posterior sucker. These are

formed chiefly of high and closely appressed papillae, the tips

of which produce a sharp erect serrate crest.

There is no true clitellum, and the genital pores have the

usual situations at XI/XII and XII a 2/a 3. Sixteen pairs of



500 Illinois State Laboratory of Natural History.

nephridiopores have been determined on somites VITI to

XXIII inclusive.

The posterior sucker is exactly circular, with a finely but

distinctly denticulated margin. It is, though not of large

size, widely exposed behind, and reaches anteriorly to XXIII

al. Its pedicle of attachment is unusually small, permitting

great freedom of movement.

Annuli and Somites (PL XLIL, Fig. 5).—I forms the apex

of the head and is divided dorsally into two small rings by a

cross-wrinkle.

II is quite distinctly biannulate and bears evident dorso-

median and dorso-lateral sensillfe.

III consists of two large annuli, of which the anterior is

slightly divided by a faint cross-furrow which is confined to

the median region. It bears the eyes, which are separated

by a space about equal to their own diameter, and three pairs

of sensillae, one of which is remarkable by reason of its

position directly above the eyes. Sections of this species

have not been studied.

IV closely approaches the triannulate condition, a 1 having

very nearly the typical relations. Three or sometimes four

pairs of sensillae are easily discernible.

V. This somite presents several interesting features. It

consists of two annuli of about equal size, both enlarged at

the margins, where the anterior one is somewhat divided into

a 1 and a 2. Three pairs of sensillae are present on a 2, but the

dorso-medians are wanting, while on a 3, almost directly

behind the dorso-laterals, appear what seem to be an extra

pair of these sense organs.

VI is also peculiar in that al is completely divided on the

dorsal side into two small annuli which appear as one

ventrally.

VII is fully triannulate and the annuli present the typical

proportions. Al is the smallest, a 2 intermediate, and a 3

the largest. A 1 and a 3 exhibit shallow ventral furrows across

their entire width, and the furrow of a 3 continues on to the

dorsal side, from the margin almost to the dorso-lateral

carinae. It cuts the annulus posterior to the sensillae. XXII,



The Hirud'mca of Illinois. 501

the last triannulate somite, lacks this subdivision, but it exists

on all other complete somites.

XXIII, in addition to the differences of papillation already

mentioned, shows peculiarities in annulus a 3, which is the

smallest of all and is differentiated from a 2 at the margins

only.

On XXIV the complete individuality of all three annuli is

suppressed, their boundaries being evident only at the

margins. On XXY only the marginal notches d Ija 3 are

indicated.
'

XXVI and XXVII are uniannulate and contracted to form

the supporting pedicle of the sucker.

The arrangement of the papillae is as follows : The median

series {mp) begins in small isolated papillae of about equal

size, usually on VI a 2 and a 3. By about IX they are well

established on all three annuli, a 3 bearing the largest, a 2

the next in size, and a 1 a very small one, and this relative

size is maintained throughout the series. A few somites

caudad they are higher, more prominent, crowded, and

elevated on a ridge. Nearing the posterior end the ridge

increases in height and the papillfe on a 2 and a 3 increase in

size, but the crowding becomes relieved and the papillie on a 1

smaller or more frequently absent. Both the ridge and its

papilla; cease completely and abruptly on XXII a 3.

The paired carinae (dip) are slightly nearer to the margins

than to the middle line. In essentials they are precisely

similar to the median one, but present the following special

features : the carina; as a whole are slightly less prominent

;

they require a greater distance in which to become fully

established, i. e., the papilla; are not supported on a con-

tinuous ridge, nor present on every annulus until about

XII or XIII ; scattered papillae of' small size are found on a 1

and a 2 as far forward as VI, but they are very small ; in the

region of full development the papilla on a 2 is by far the

largest of this series and generally larger than any of the

middle series, and the papilla on a 1 is very small and

frequently absent, especially in the posterior region. The



502 Illinois State Lahnraiorrj of Natural History.

last papilla of the series is on XXII a 3 and is displaced

slightly mesiad.

On somites XXIII to XXVI the carinre are absent and are

replaced by four pairs of large papillae. These form two

short series which if continued forward would pass midway
between the median and lateral carinae. .The first pair,

situated on the larger annulus of XXIII, is the largest, the

next somewhat smaller, while the others diminish rapidly

and converge posteriorly. Yery minute papillte may occur

on the preanal somite.

All of the papillae ^enumerated are of prominent conical

form, sharp-pointed, and high. Their summits bear a con-

tractile apex, which in some cases is almost filiform in exten-

sion, in others short truncate in contraction. Around the

base of this appendage a few smaller points may be clustered.

In addition to those more prominent papillae which have

been described, a more or less complete irregular series of

small papillae forms a dorso-marginal line, external to which

a few are scattered along the margin and a still smaller

number on the internal side. None of these are ever elevated

on a ridge.

The metameric sensillae have the following positions (PI.

XLII., Fig. 5). The dorso-medians {md) are just a little way to

the mesial side of the middle of the area between the median
and the dorso-lateral carinae, and are quite easily traced as

far forward as II. A curious* circumstance which requires

investigation is that a pair appears to lie "on the integument

directly above the eyes. In the middle body region the

papillae of this series are slightly elevated and they are every-

where the most conspicuous. The dorso-lateral sensillae (dl)

are almost as evident on the head as the dorso-median, but

much less so on most of the body somites. They are just

external to the large papillae of the dorso-lateral series, but

after the suppression of their guardian .papillae, on XXIII,

they stand out much more prominently in their isolation.

The dorso-marginals (<im) become visible on III and continue

* Inasmuch as the eyes seem to be the representatives of the dorso-median sensillae
of somite III and to have undergone no shifting.



TJie Hlrndinca of Illinois. 503

distinct to XXV, on which latter they approach very close to

the dorso-laterals. By the fusion of the sensillae of these two

series on XXVI and XXVII but three pairs remain. Very

minute supra-marginals {sm) are also present on most of the

annuli. Near the margin of the sucker one or two very

regular circles of eight sensillae are ranged.

Iieprodiicttve Orgmis.—The six pairs of testes are in the

anterior ends of somites XIV to XIX, extending somewhat

into the preceding somites. The enlarged region of the

sperm-duct (epididymis and ductus ejaculatorius) forms a

coil or two, and its full length when extended laterally

scarcely reaches to the margin of the body at the male pore.

The prostate cornua are short and wide. The anterior and

dorsal lobe of the ovary, which represents the closed end of

the sac, is large and prominently projecting.

Alimentary Canal.—Pharynx slender and very extensible,

its glands small. The same number and general arrangement

of the gastric cieca as in P. parasitica are found in this species,

but they are much less subdivided and branched.

Color.—The colors of this species are generally dull and

uniform. Very commonly the entire body is a light or darker

green or brownish green with a few flecks or lines of deep

green and an obscure pale yellow border. Sometimes the

pattern is more definite, as in the following case : The entire

central region of the dorsum is of a brownish green color

which on the neural annuli extends to the margins in the

form of narrow sharp-pointed projections, by which a series

of large yellow marginal spots are separated from one another

and thus barely escape forming a continuous yellow border.

Six or seven elongated light yellow spots form a median series

and alternate with short dark greenish brown longitudinal

lines. Smaller, more or less confluent light yellow spots mark

the lateral carinae. The head is marked by an irregular green-

edged dark brown "spread eagle" figure, which leaves a large

anterior and a pair of posterior lateral light spots.

Habits.—This species to a great degree lacks the social

instincts of most glossiphonids. A far larger number of

specimens are found singly than in company. In the neigh-



504 Illinois State Laboratory of Natural History.

borhood of Philadelphia they are most frequently found in

meadow brooks, adhering to stones, or attached to frogs and,

during the spring, to toads. They frequently enter the shells

of living mussels, which they probably attack. During the

spring at least they are voracious blood-suckers, and along

the Delaware River congregate at points where fish are

cleaned and the waste thrown into the water.

ICHTHYOBDELLIDiE.

The collection contains several specimens of a small

species of Piscicola and another probably of Plscicolarla,

both parasitic on several species of small fishes. The

material is not sufficiently well preserved to permit of

determination or description. This family is further repre-

sented only by

AcTINOBDEliliA gen. nov.

Generic Characters,—The head small, not explanate ; the

posterior sucker large, hemispherical, with a marginal circle

of slender processes ; the complete somites with six secondary

annuli of unequal size.

Actinobdella inequiannulata sp. nov.

Diagnosis.—A median series of papillfe on annuli b 3 and

h 5 ; annulus b 5 the longest, b 4 the shortest, in complete

somites; male orifice at XI/XII, the female at XII &4;
acetabular papillae about thirty, provided with adhesive

glands.

General Description.—The single specimen representing

this species is of small size ; the total length is 9.7 mm., the

greatest width 1 mm., and the diameter of the posterior

sucker about 1.8 mm. The sexual organs are very incon-

spicuously developed, and it is possible that the species may
reach a somewhat larger size.

The form is slender (PI. XL 1 1 1., Fig. 8), with the margins

of the body parallel for almost its entire length, but suddenly

contracted posteriorly to constitute the narrow pedicle of



The Hirudinea of Illinois. 505

the conspicuous sucker, and gently tapering anteriorly to the

broadly rounded upper lip. Depressed throughout, with the

dorsum convex and venter flat ; the margins somewhat sharp.

There is no expanded anterior sucker (PI. XLIIL, Fig. 8)

or head as in typical ichthyobdellids, but this end of the body

is formed like a glossiphonid or, excepting the character of

the mouth, more like a nephelid. The lip is broad and

rounded and in this example is turned in ventralward. On
the dorsal side it is divided into annuli as described under

the caption Annuli and Somites. The ventral surface pre-

sents a very deep cavity from out of which rises a prominent

rounded elevation, near the summit of which the pore-like

mouth is situated. The posterior boundary of the sucker is

formed by somite Y. No pigmented eyes can be detected, but

an opaque spot on the third and fourth rings may possibly be

eyes, though appearing more like a gland.

No clitellum is developed. The male genital orifice (PI.

XLIIL, Fig. 8, d^) is a minute pore situated in a transversely

extended elliptical disc at XI/XII ; but on the ventral side

the annuli" XII b 1 and b 2 are obsolete and the male
disc therefore somewhat overspreads annulus b 3. The female

pore ( 9 ) is in the form of a small transverse slit in annulus

XII &4 and, owing to the great reduction of 6 1 and ft 2,

appears to be separated from the male opening by only one

and one half annuli.

Most remarkable of all of the external features of this

leech is the posterior sucker (PI. XLIIL, Fig. 8-10). It is

much wider than any part of the body, of hemispherical

form, largely free on all sides, and supported by a narrow

central pedicle. The ventral surface (PL XLIIL, Fig. 10) is

very deeply cupped, and in the specimen described the rim is

somewhat contracted, making the diameter of the opening

somewhat less than that of the internal cavity. From the

inner face of the sucker, a short distance back from the sharp

margin, spring about thirty (exactly thirty in this example)

slender finger-like processes, which project more or less

freely into the cavity. Owing to their contractile nature

they may vary in length and diameter, but when extended



506 Illinois State Laboratory of Natural History.

are about .4 to .5 mm, in length and perhaps .1 in diameter.

Each one (PI. XLIII., Fig. 11) contains a central gland duct

or perhaps a group of ducts surrounded by a sheath of

muscle fibers springing from muscular ridges which pass like

radii down the inner face of the sucker. The gland ducts

arise from a circle of glands which appear as a ring of whitish

spots arranged around the sucker about half-way between

the margin and the pedicle, and which raise the outer face

into a slightly marked encircling ridge. The anus is incon-

spicuous and appears to be situated in the usual position

posterior to somite XXVII.
Annidi and Somites.—It is obviously unsafe to assign to a

species all of the details of annulation exhibited by a single

specimen. The arrangement of the annuli in certain regions

is so obscure and appears so differently under different con-

ditions of fixation and preservation, and, moreover, is so sub-

ject to individual variation, that the typical conditions in

many species can be determined only by the careful study of

many individuals. What follows, therefore, must be con-

sidered as applying in entirety only to the type specimen.

The characters of the complete somites and the composition

of most of the incomplete somites will in all probability be

confirmed by the study of further material.

As the type specimen is interpreted the somites are consti-

tuted as follows (PI. XLIII., Fig. 8, 9) :—

I to IV are uniannulate and the furrows which separate

the first three annuli are faint. No sensillse are recognizable.

V, VI, and VII are biannulate, with three pairs of

distinct eensillae on the first annulus of each. In each case

the second annulus is somewhat the larger.

VIII is triannulate, and a 3 is somewhat larger than its

fellows and subdivided by a faint furrow. The sensillse are

on rt 2.

On IX we find a 1 subdivided equally into b 1 and 6 2 by a

shallow furrow, a 2 more distinctly split into a larger anterior

and a smaller posterior ring, of which the former bears the

three pairs of sensillse, and a 3 subdivided equally.

X is similar to IX except that 6 5 is considerably larger



The Hlrudinea of Illinois. 507

than b 6 and the secondary furrows are more nearly equal

to the primary.

XI is a typically complete somite and presents characters

which are found with some slight individual variations as far

back as XXIV inclusive. In all of these the annuli are very

clearly indicated both on the dorsal and ventral surfaces.

^ 1 is divided equally into b 1 and b 2, which are quite short

rings unmarked by any papillae ; a 2 is very distinctly divided

into a long 63, which bears a large median cutaneous papilla

and the three pairs of metameric sensilltp, and a 6 4, of half

the size or less, which is the smallest annulus of the somite

and bears no papillae; a 3 is cut into b5 and 6 6, of Avhich

the former is the largest annulus of the somite, both in length

and breadth, and which bears a large papilla similar to that

on 6 8, while 6 6 is a simple unadorned ring equal to b 1 or

b 2. Thus each complete somite is divided into six annuli of

unequal size, and, leaving out of sight the limits of the

somites, this region of the body exhibits a regular alternation

of groups of three equal small rings with groups composed

of two large rings separated by a very small one. Each

of the large rings is marked by three cross ridges which

appear to be due to transverse muscle bands, while the

narrow rings present only two siich ridges, b 4 sometimes

only one ridge.

The cutaneous papillae (PI. XL 1 1 1., Fig. 8) are rather con-

spicuous conical elevations with the long axes of their ellip-

tical bases directed longitudinally. In the middle region they

are strictly confined to the annuli indicated,' but posteriorly

somewhat overlap the succeeding secondary annuli. On
other specimens they will probably be found to begin further

forward than on the type, as opaque thickenings of the integu-

ments appear in the proper regions of somites X and IX,

though there are no elevations.

Of the dorsal sensillae (PI. XLIIL, Fig. 8) the supra-

marginals cannot be distinguished, but the dorso-marginals

((Zm), dorso-laterals (rf/), and dorso-medians (md) are obvious,

and are very regularly arranged on all somites from V to

XXVI. Peripherad of these points they have not been traced.



508 Illinois State Laboratory of Natural History.

The distances separating the two dorso-medians and the dorso-

laterals from the dorso-marginals are about equal and some-
what less than that between the dorso-medians and dors'o-

laterals.

XXV exhibits very much less distinct secondary furrows,

the annuli all of about equal size, and the somite prac-

tically triannulate. This is also the last somite to bear

distinct papillae.

XXVI is strictly triannulate, with the sensillee on a 2,

but lacking any distinct papillae and secondary furrows. In

the figure, XXVII is represented as divided into three narrow
rings, but owing to a distortion of this region it is quite im-

possible to make a satisfactory determination. In some
lights and positions there appear to be three rings here, -in

others two, and two drawings made at different times and
independently illustrate the two interpretations.

The color has faded to a uniform gray. Nothing of the

internal organization could be learned by studying the speci-

men, either stained or unstained, in various clearing media,

and consequently this description leaves much to be desired.

The position of the ganglia and lateral nerves was deter-

mined by a partial dissection of the mid-ventral region of

two somites.

HIRUDINID^.
Macrobdella Verrill.

Macrobdella decora (Say) Verrill.

Hlrudo decora Say ('24).

Hirudo decora Leidy ('68 J.

Diagnosis.—Copulatory glands opening by four pores

arranged in a quadrate figure on XIII i 6 and XIV h 1 and b 2
;

male pore at XI/XII or XII b 1, female.at XII/XIII or XIII b

1 ; somite XXVI has annuli («1 +a2) + a3; annuli VII a 3

and VIII a 1 relatively large and partly subdivided dorsally

;

atrium short and spherical; alimentary canal with exten-

sively developed cseca ; denticles small, about 65 on each jaw,

and monostichodont ; color pattern metameric.



The Hirudinea of Illinois. 509

General Description.—This fine leech is so well known and

has been so fully described by Say ('24), Leidy ('(38), Verrill

('74), and Brooks ('82), that only a few notes on certain

features need to be added.

The anterior sucker is provided with a rather wide unseg-

mented and very mobile border which materially increases

its capacity for expansion. Anteriorly a distinct median

emargination corresponds with a deep ventral sulcus, which

divides the upper lip and is flanked by a pair of scarcely less

deep sulci. When strongly contracted the upper lip is folded

and turned into the buccal chamber, where it is almost

entirely concealed by the lateral lobes formed by the margins

of somite lY.

A well-marked clitellum is seldom present. In one example

it is firm and thick and extends over eighteen annuli, from

the posterior half oi Xd5 to XIV d 2. In the fully retracted

state the male pore appears as a rather large opening on the

furrow XI/XII, into which the surrounding rugosites are

converged and inflected, forming a small sinus perhaps com-

parable with the pit of Philohdella. These inflected parts

may be everted, in which event they form a prominent conical

organ having deeply fluted sides and the small male aperture

at the apex. As protrusion of the parts takes place annulus

XII ^1 becomes relatively longer at the middle and comes

to support almost the entire base of the papilla, so that the

male pore now lies well within the boundaries of this annulus.

I have never seen any other penial organ protruded.

When fully developed each of the four copulatory gland pores

lies in the center of a prominent rugous area, the four being

arranged in the form of a square. The anterior pair extends

half over annulus XIII I? 6 and equally over XIV dl, and

the posterior pair holds a similar relation to XIV /; 1 and d 2.

The pores consequently open on the line of the furrows

separating these annuli.

Annulation.—The external annulation differs but slightly

from the closely allied species M. sestertia, figured by Whitman
('86). The principal differences (characters stated as they

occur in M. decora) are as follows : 1, The annulus IV {a 1 +



510 Illinois State hahoratory of Natural History.

a 2)—that bearing the third pair of eyes—is distinctly longer

than IV a 3, and in some examples the furrow al/a.2 is

more or less distinctly discernible. 2. The annuli VII a 3

and VIII a 1 are relatively very much longer, and on the

dorsal side the secondary annuli and furrows are distinctly

developed, 3. XXVI a 1 is always marginally and some-

times completely separated on the dorsal side from a 2.

4. The relative lengths of the annuli of complete somites

differ in the two species. In M. sestertia the neural annulus

(a 2) is figured as of equal or greater size than the secondary

annuli, while in M. decora it is typically shorter than any of

these in the same somite.

Rejiroductlve Organs.—Testes (PI. XLIV., Fig. 23, i)—ten

pairs, situated at XIII/XIV to XXII/XXIII inclusive. The

vasa deferentia (vd) are glandular, and follow sinuous courses.

In somite XI they become narrow and lose their glandular

coating. Opposite to ganglion XI they turn abruptly into

the compact, massive, much convoluted epididymes (ep).

From the posterior end of each of the latter a wide somewhat

folded and coiled ductus ejaculatorius (de) leads to the term-

inal organ. Just before plunging into the outer glandular

and muscular wall of the latter the ducti become constricted,

and then form a pair of slightly enlarged sacs which proceed

upward side by side to open together into the end of the male

invagination (PI. XLIV., Fig. 22). This terminal male organ

(PI. XLIV., Fig. 23); which is evidently intermediate in its

structure and character between the atrium of Hcemopis and

the genital pit of Philohdella, is, when entire, spherical in

shape ; but when its external coat of muscle fibres and pros-

tate glands {pg) is stripped off, the lining sac is found to be

somewhat pyriform {ati).

The ovaries (PI. XLIV., Fig. 23, oy) are large and globular,

situated just behind ganglion XII, and ventral to the nerve

cord. Short paired oviducts (ocZ) unite in a common oviduct

{ode) without any evident gland at the point of junction.

The vagina {va) is short, of irregular diameter, and bent on

itself.

The copulatory glands (PI. XLIV., Fig. 23, cgl), the external



The Hirudinea of Illinois. 511

openings of which have been described, form a conspicuous

mass occupying the posterior half of XIII and the entire region

of the floor of XIV included between the vasa deferentia.

Alimentary Canal.—The jaws differ greatly from those of

Philohdella and resemble those of Hirudo ; they are more than

twice as long as high and each bears about sixty-five fine

monostichodont teeth. The remainder of the canal is very

like that of DiplohdeUa. Each somite from X to XVIII
inclusive is provided with two pairs of c?eca which are very

spacious from XIII caudad. The large posterior pair, which

arise from the stomach in XIX, reach backward clear into

XXIV or XXV.
Habits.—Marrohdella is probably strictly aquatic and is a

true blood-sucker. It attacks man, cattle, turtles, frogs,

fishes, etc., which enter its domain, and is frequently found

gorged with blood. However, this is not its exclusive food.

In the spring great numbers of frogs' eggs are devoured. In

the neighborhood of Philadelphia these are sucked from the

masses of jelly after the gelatinous envelopes have been cut

by the leech's teeth. Large numbers of tubificid worms
have also been found in the cfeca. Whitman ('86) gives an

account of the sensory reactions of this species.

Philobdella Yerrill.

Philobdella gracile sp. nov.

Philobdella Jloridana Moore ('98), not Verrill ('74).

Diagnosis.—Copulatory gland pores in two nearly counter-

part groups related respectively to the male and female

genital orifices ; male pore at XII i^" 2/a 2, in mature examples

opening into a conspicuous deep pit, female pore at XIII b 1

;

alimentary canal of Hiemopis type, the denticles about 35,

partly distichodont ; annulation essentially as in Hcemopis

marmoratis ; color partly non-metameric blotches.



512 Illinois State Laboratory of Natural History.

General Description.—The largest extended specimen has

the following measurements :

—

mm.
Totallength, 84.

19.

. 7.8

7.

. 3.

2.5

. 2.8

1.5

4.3

Length to male pore, ....
Greatest width (about XX),
Width at male pore, ....
Width at anus, .....
Depth at XX,
Depth at male pore, ....
Depth at anus, .....
Diameter of posterior sucker,

This is a very pretty leech of moderate size and slender

graceful form. The preserved specimens are depressed

throughout, except just posterior to the mouth, the ventral

surface is flat, the dorsal gently convex, with an evident

tendency to rise to a rounded median ridge. In some exam-

ples the middle two thirds, or so, of the body remains of

nearly uniform width; in others the outline tapers gently and

regularly from the place of greatest width forward to the

mouth.

Probably the body of the living leech has a texture about

like Hamojns lateralis, as the muscles and botryoidal tissue

display a similar relative degree of development. Except for

a few wrinkles and the very slightly elevated sensillae the

surface is quite smooth.

All of the annuli are clearly marked by smooth even fur-

rows, but owing to the absence of any well-marked transverse

ridges they are not angulated and the margins of the body do

not appear denticulate. Most of the annuli, however, do

show a faint incipient transverse furrow, dividing them into

approximately equal halves, the posterior one of which may
be marked by a very faint raised line.

As in Hiriulo, but unlike Hcemojns, there is a distinct very

narrow unsegmented margin or border to the anterior sucker

(PI. XLIV., Fig. 13), which is separated on the ventral side

by a shallow trench from the actual mouth rim. The mouth
and sucker are small. A median sulcus divides the ventral



The Hirudinca of IlUnois. 513

surface of the upper lip deeply into two halves, hut fades out

posteriorly ; at least one fainter sulcus appears on each side.

Somites I-IV constitute the lip and sucker, and the united

annuli of V form the postoral annulus.

The five pairs of eyes (PL XLIV., Fig. 12, 19) present

the arrangement usual in the family, except that the second

and third pairs are closely approximated, owing to the posi-

tion of the latter very close to the anterior horder of somite

IV. The fourth pair also is somewhat in advance of the line

of sensillie.

No specimens have heen seen in which the clitellum is

sufficiently developed to permit of the determination of its

form and extent.

As A^errill ('74) long ago pointed out, the external genital

region (PI. XLIV., Fig. 16) is very remarkable; in some
respects, indeed, unique among known leeches. This is true

not only of the elahorate adhesive arrangements, which are

probably important aids to successful copulation, but also of

the location of the genital apertures. The features of this

region have been described by Moore ('98) from examples

collected in Louisiana, but are now figured for the first time.

The figure is a composite of the three specimens which this

collection contains and which differ from one another in cer-

tain particulars.

Comparison of the previous account with this figure will

bring to notice some disparity in minor details, due to the

fact that almost every specimen presents some individual

peculiarities. It is very probable that this results not more
from individual variability than from the temporary, seasonal,

and developmental character of the structures concerned.

In specimens sexually inactive the male pore appears

near the anterior margin of XII a 2 ; the female pore, on XIII
b 1. They are surrounded by a more or less wrinkled area in

which appear a variable number of copulatory gland pores

more or less conspicuously developed. Omitting consider-

ation of intermediate states the active condition is represented

in PI. XLIV., Fig. 16. The surface immediately surround-

ing and succeeding the male pore is inflected as a deep pit



614 Illinois State Lahoratortj of Natural History.

(d), on the anterior face of which the male pore is carried

and concealed by the slightly overhanging* margin. Thus is

formed, probably through the contraction of the dorso-ventral

muscles, a sort of genital sinus inclining dorsad and cephalad

deeply into the body and opening by a wide mouth on to the

surface of annuli XII « 2 and d 5.

The neighborhood of the female pore is reciprocally elevated

as a sugar-loaf shaped papilla, inclining caudad and ventrad

and consequently well adapted to occupy the male pit, in

which event the female pore ( ? ), situated at its apex,

would come into contiguity with the male pore near the

bottom of the pit.

The copulatory gland pores (cgp) are much more conspic-

uous than in the individuals first described, but are subject

to much variation. Typically they are arranged as follows :

In the male system {d'cgp) a pair (concealed in the figure) is

placed symmetrically beside the male pore ; a second pair,

and sometimes an additional median one, is situated just in

front of the anterior border of the pit ; on the furrow

XII rt 2/<^ 5, just external to the pit, is a third pair; a

fourth pair is found just abreast of the last but on the lateral

walls of the pit within its mouth ; and, finally, a median pore

appears on the sloping posterior face of the pit cephalad of

the third and fourth pairs.

An almost exact reversed counterpart of the male system

is found in the female system of adhesive organs ( 9 cgp). It

is described in the order in which the pores are supposed to

correspond with those of the male system as respectively

enumerated. The first pair occupies the sides of the female

papilla close to the genital orifice ; the second is found on

annulus XIII b^, caudad and laterad of the papilla and

sometimes accompanied by a median one ; the third and
fourth pairs of the male system are represented by a

single pair in the female system, which is just caudad of the

male pit on annulus XII ^ 6. A median pore situated just pos-

terior to these completes the parallelism.

*The ventral surface being turned uppermost.



The H'lrudinca of Illinois. 515

Besides those mentioned, two or three additional pairs are

located far from the middle line on annuli XIII (^2, a 2,

and d5.

Each of these pores is the crescentic or slit-like external

orifice of a little subcutaneous bursa, usually tilled with a

more or less hardened substance which may raise the integu-

ments into a small papilla and is probably the secretion of a

mass of glands {cgl) occupying the whole of the middle region

of somites XII and XIII and covering the walls of the male

pit internally.

Seventeen pairs of nephridiopores (PI. XLIV., Fig. 13, 14)

are situated on small papillae near the posterior margins of

annuli VII al to XXIV ^J* 2 inclusive. The posterior are

entad, the anterior ectad, of the ventro-lateral sensillse.

Annuli and Somites (PL XLIV, Fig. 12-15, 18, 19).—Ex-

cept in a few minor respects the incomplete somites possess

the same number of rings as in Mdcrobdella and Hcemajris

marmoratis.

Fifteen somites (IX to XXIII inclusive) are complete and

quinqueannulate, bl+t'l+ a 'l+b 6-\-b (y. In each of these,

except IX, rt 2 is just perceptibly shorter than the others and

is less likely than they to show the depressed transverse

line, though the raised line just behind the sensillfe is quite

as distinct.

The sensillfe are very regular in arrangement but very

small. They appear as w^hite circular spots, and, in the best

preserved examples, are distinctly but very slightly elevated

above the surface. They encircle the exact middle of the

annulus. The dorso-medians {md) are very close together,

scarcely an annulus length apart. About twice this distance

separates these from the dorso-laterals [dl] ; from the

dorso-laterals to the dorso-marginals (dm) and also from the

latter to the supra-marginals {sm) the distances are slightly

greater than that first mentioned. Owing to the flatness of

the ventral surface the relative positions of the sensillai as

shown in Figures 13 and 14 represent accurately the

distances which separate them.

There are eight incomplete somites at the anterior end.



516 Illinois State Laboratory of Natural History,

I is incompletely separated from II and bears but one pair of

metameric sensillae. II is a narrow imperfectly differentiated

annulus bearing the first pair of eyes and, externally to these,

three pairs of sensillfe. Ill is also uniannulate, and the

second pair of eyes Avhich it bears represents the dorso-lateral

sensillfe, the other three pairs being unmodified.

IV is biannulate {al -\- a '2)-\-aS. The first ring is wider

than the second, and its composition is indicated by an inter-

rupted furrow which passes across the third pair of eyes but

anterior to the other sensillee. Y differs from IV only in its

somewhat greater length and its relation to the mouth.

VI and VII are each triannulate ; the latter is considerably

the larger, but in each the annulus a 3 is dorsally about two

fifths of the entire length of its somite and in VII shows a

slight furrow all around. The furrow VI a 1/a 2 disappears

ventrally.

VIII is quadriannulate ; a 1 is longer than a 2 and faintly

subdivided all around, but is not equal to VII ad ; d 5" and

d 6 are fully developed and about equal to a 2.

In IX the relative size of the annuli is dl^=d2 <a2 «^5=/^6
;

in X, dl=d^=a'i <^5==(^6 ; and in XI and succeeding somites

dl—d2=^l?5=d6> a2. The posterior annuli of XII and the*

anterior of XIII are somewhat contracted in length.

In XXIII, d5 and d6 are relatively slightly shorter, while

in XXIV they are no longer distinct, the separating furrow

being very shallow, so that this is counted as a quadri-

annulate somite. Bl and d 2 are longer than a 2.

XXV is a contracted quadriannulate somite in which the

following relative proportion exists in the lengths of the

annuli of the specimens examined : dl^=a3 > a2~—d2.

XXVI presents the following variations : In the specimen

drawn it is a single large annulus, particularly long at the

sides, where a faint emargination and slight dorsal depres-

sion indicate an incipient division at about the middle.

The sensillse are fully developed and lie well toward the pos-

terior margin of the ring. Another example from the same
lot has this somite very distinctly and completely divided on

the dorsal side into two annuli, of which the anterior is almost



The Ilirudinea of Illinois. 517

twice the length of the posterior, except at the margins, where

they are more nearly equal. The sensillie are very distinct and

are all placed very close to the anterior margin of the second

annulus which, therefore, in spite of its smaller size, is re-

garded as (a 2-r(/ 3).

XXVII is irregular and more or less divided into two rings,

especially at the margins. The anus cuts into the posterior

margin of the somite, which at that point is irregularly lobed.

The sensillfe are close to the furrows by the side of the anus

and the dorso-medians are widely separated. XXVIII is

somewhat distinct from the sucker and bounds the anus

posteriorly.

Reproductive Organs.—Two examples were dissected, and

the small size of the organs renders it probable that they

were taken at a time when these were not in full activity.

The internal organs of generation (PI. XLIV., Fig. l7) are

very simple.

But seven pairs of small testes {t) were found at the anterior

ends of somites XIV to XX. The very slender vasa deferentia

{vd) reach to ganglion XI, where they bend back on them-

selves and become almost immediately much enlarged and
thrown into several folds {ep, de). This region appears to

correspond to both the epididymes and ducti ejaculatorii of

Hreniopis. The two ducts immediately open together into a

small thin-walled bursa, and the bursa communicates with

the pit as above described. There is no muscular atrium

and no penis. Numerous muscular fibers pass between the

ventral integuments in the neighborhood of the pit and the

dorsal integuments. Ganglion XII is crowded caudad from

its normal position to the posterior end of its somite.

The female organs (PI. XLIV., Fig. 17, 21) are of the

Hirndo type. In the specimens examined they are sym-

metrically related to the body axis. The ovaries (ov) are

sausage-shaped and each is folded on itself. Separate slender

oviducts (ov) lead to an unpaired organ, into the large end of

which they open. There is no evident external distinction

between glandula albuginea, oviductus communis, and vagina,

but the three together are combined in a slender claviform



518 Illiyiols State Laboratory of Natural History.

organ, which is doubled on itself forward and opens by a duct

on the external papilla.

Alimentary Canal.—Except for the jaws the alimentary

canal is most like that of H(emopis. It is straight and simple,

with one pair of large posterior cseca and numerous small

pockets, usually two pairs per somite along the middle region.

The jaws, however, are of a very different form, resembling

those of Diplohdella. They are very high and prominent, the

height being greater than the length. The denticles are

small, sharp, and in part at least ranged in paired series

(PI. XLIV., Fig. 20). It is quite possible to draw them
apart with needles and to display the groove which divides

the two rows.

Color.—The colors are described from alcoholic specimens

which are evidently somewhat faded and otherwise altered.

Light brownish drab above, yellowish below. A distinct con-

tinuous narrow yellow line marks the dorsimesion, becoming

very faint anteriorly while posteriorly it is more or less broken

by intrusion of the ground color. A pair of rather broader but

less distinct yellow lines mark the margins. Between the dorso-

marginal and dorso-lateral sensillse on each side is a row
of small irregular deep brown spots, generally well separated

but at intervals becoming aggregated and more or less con-

fluent. A very few faint and suffused brown spots are scat-

tered over the dorsal surface. Ventrally the only markings

are some rather larger reddish brown spots which are chiefly

aggregated along the margins and become in places confluent.

Habits.—That this leech feeds in part at least on weaker

creatures is shown by the presence of remains of earthworms

{Allolobophora) in the canal. One of Verrill's specimens of

P.Jioridana was captured in the act of swallowing a small

lumbricoid worm. The structure of the alimentary canal

would also indicate a diet of this character varied by an
occasional meal of blood.



The Ilirudinea of Illinois. 519

HiEMOPIS SaviGNY.

Haemopis marraoratis (Say).

Hiiudo martnorata Say ('24).

Aulastomiim lacustre Leidy ('68).

Diagnosis.—Annuli VII I? 5 and 5 6 and VIII /? 1 and d 2

indicated on the enlarged primary annuli but not fully devel-

oped ; d pore on 32 (XI d 6) or 31/32 (XI l?5}d6), ? pore

on 37 (XII /^6)or 36/37 (XII d5/l?6); atrium and vagina

reaching into somite XVII; ovaries just behind ganglion

XIV.
General Description.—This species reaches a greater size

than is attained by any of the Illinois examples, the largest

of which measures :

—

mm.
Total length, 104.

Length to d' pore, . . . . . . .22.
Greatest width, (XVII), . . . . . 15.5

Width at cf pore, 12.
" " anus, 7.7

Depth at XVII, Q.5
" " d pore, 3.8
" " anus, 2.5

Diameter of posterior sucker, . . . . 6.5

Owing to (he great development of botryoidal tissue the

body is exceedingly soft and consequently varies greatly in

shape, when alive, according to the various states of rest and

activity, in preserved specimens, as a result of the different

methods adopted for fixation and preservation. When
actively swimming, and especially when the stomacli is

empty, the body is elongated and flattened but never very

slender. (This is nearly the condition of the example meas-

ured.) The width is generally greatest at about the middle

of the body, but differs very little between the clitellum and

the last complete somite. In preserved specimens the clitel-

lum is frequently the widest part of the body. Anterior to

the clitellum the body tapers rapidly to the broadly rounded



620 Illinois State Laboratory of Natural History.

prostomium and is less flattened. When exploring, but not

swimming, the form is much less depressed and more terete,

and may become much more extended and slender. The
resting attitudes are varied and interesting. The body may
be contracted to an ovoidal form, the upper lip is usually

inflected, and the anterior end of the body variously inroUed
or folded on the ventral surface.

Living specimens held in the fingers are so soft and hang
so limp that they appear more like pieces of dead tissue than
living animals. This peculiarity also enables them to squeeze

into the most narrow clefts and thus often to escape from con-

finement. None of the cutaneous sense organs are elevated

upon papillie, so that the surface appears perfectly smooth.
Both living and well-preserved specimens are strongly

annulated (PI. XLV., Fig. 24), and in the latter eachannulus
is raised into a transverse ridge situated about one third of

the length of the annulus from its posterior border. As a

result the margins of the body usually appear rather decidedly

serrate. In some specimens such elevated ridges extend

around the entire circumference of the body.

The anterior sucker (PI. XLVL, Fig. 34) is mobile and
comparatively large, but without any definitely expanded
disc. The mouth is large. The upper lip is broad and
bluntly rounded, crenulate on the margin, but almost per-

fectly smooth and undivided ventrally. Several rows of labial

sense organs are situated around its margin and on the pre-

ocular and oral annuli. Dorsally the furrows which divide

it into annuli may be very faint, but are usually discernible

for a portion of its width (PI. XLVL, Fig. 33).

Of the five pairs of eyes (PI. XLVL, Fig. 33) the first three

pairs are conspicuous and arranged in a regular arc on the 2d,

3d, and 4th annuli; while the fourth and fifth pairs are more
widely separated on the 6th and 9th annuli respectively, and
are increasingly smaller and deeper and, as a consequence,

more obscure. Their optical axes are variously directed ; the

first pair forward and slightly outward, the second decidedly

outwards and forwards, the third directly outwards, the fourth

outwards and backwards, and the fifth backwards and some-



TJw Iliruilinea of Illinois. 521

what outwards ; thus, together, they cover an arc of perhaps

ICO".

Aniiulus 6—V {a l~a 2)—unites with 7 (V a 3) ventrally to

form the hroad postoral ring ; hut the immediate oral ring or

lower lip is a rim, more or less narrow and more or less dis-

tinct from 6, which is contributed by 5 (IV a 3). At the

sides the mouth is bounded by the 4th and 5th annuli, which

coalesce laterally (PI. XLVL, Fig. 33).

In mature examples the clitellum (PI. XLV., Fig. 24) is

very distinct and equally well developed dorsally and ven-

trallj'. It is smooth, thick, and firm, and at its posterior

end as wide or wider than the succeeding annuli. Posteriorly

it is straight, anteriorly concave ; and it extends over fifteen

annuli (X d 5-XIII a 2 inclusive).

The Illinois specimens exhibit no variation in the position

of the genital pores, which are, invariably, the male in XI ^6
and the female in XII d6. The male orifice is situated close

to the anterior border of its annulus, which enlarges

mesially and encroaches slightly on the preceding annulus-

Occasionally the region immediately surrounding the orifice

is elevated as a low broad papilla. The size of the actual

opening, as well as its form, difl^ers according to the state of

retraction or protrusion of the penis and related parts. The
female pore is rounded or slit-like, is smaller than the male,

and, like that, is usually close to the anterior border of its

annulus though more liable to shift as far as half its width

caudad. The annulus is enlarged and its anterior furrow

becomes obsolete in its middle part.

The relatively small posterior sucker is circular, broadly

attached, thick posteriorly, and projects by about one third

of its diameter beyond the body, its anterior margin reaching

to XXV a 2. Just anterior to it is the large anus with its

much wrinkled margin cutting into XXVII. Prolapsus of

the rectum frequently occurs in individuals which contract

excessively as a result of irritation..

There are 17 pairs of nephridiopores situated just anterior

to the posterior margins of the ^2 region of somites VIII to

XXIV inclusive (PI. XLVL, Fig. 34). Each is in a faint



522 Illinois State Laboratory of Natural History,

depression hounded anteriorly by a slight forward displace-

ment of the transverse ridge. The anterior pores are exactly

in line with or very slightly mesiad of the ventro-lateral

sensillte, while the posterior lie well inside of this line.

Annitli and Somites (PI. XLVI., Fig. 33, 34).—Somite I

can seldom be distinguished as a distinct ring, but in Avell-

preserved preparations a pair of dorso-median sensillfe may
always be found anterior to and a little mesiad of the first

pair of eyes. Sometimes the furrow may be discerned at and

near the middle line, but it is always very faint and incom-

plete. This region bears numerous labial sense organs,

which are arranged in about eight transverse rows ; but,

except in one case in which two were found, only the one

pair of segmental sensilhe can be distinguished.

Somite II consists of a single narrow annulus imperfectly

distinguished from the preceding and succeeding annuli.

The posterior furrow sometimes extends quite to the lateral

margins of the lips, but is usually very faint and imperfect.

This somite bears the first pair of eyes, together with dorso-

median, dorso-lateral, and dorso-marginal sensillfe, the latter

being very difficult to distinguish from the labial sense

organs.

III is also uniannulate but is more distinct, though here

again the furrows are frequently incomplete. The dorso-

median sensillae are small but distinct, while the lateral and
marginal pairs are quite evident. A few goblet-shaped sense

organs form a broken transverse series.

IV is biannulate, the two annuli uniting at the margins to

form the lateral boundaries of the mouth. The anterior

annulus is somewhat the wider and bears the eyes and the

full set of sensillfe toward its posterior part. It is conse-

quently regarded as potentially constituted of the two primary

annuli « 1 and ^2. Each annulus bears one row of goblet-

shaped organs.

V is a more fully elaborated biannulate somite. The
anterior annulus is decidedly the larger, and exhibits on the

dorsal side two transverse series of goblet-shaped organs

which are ventrally united into one. A full set of metameric



The Ilirudinea of Illinois. 523

sensillfe is present on the posterior portion of the dorsal

surface, but the ventral ones have escaped notice, if present.

The second, smaller annulus (^3) has one series of goblet-

shaped organs.

On YI a partial furrow indicates the line of division between

the constituents a 1 and a 2 of the much enlarged an-

terior annulus. The extent of this furrow is variable. It

extends from the dorsal mid-line, where it is deepest, laterad

sometimes as far as the dorso-marginal or even to the supra-

marginal sensillje, but may reach as far as the eyes

only. All of the sensilLne, both ventral and dorsal, are

well developed and, including the 5th pair of eyes, are on the

a 2 constituent. Annulus a 3 is the last on which a complete

row of goblet-organs is distinguishable,

YII is triannulate, a 1 being slightly shorter than a 2 and

a 3 much longer, the latter constituting about two fifths of the

total length of the somite. Occasionally in large specimens

a very evident furrow divides this annulus into two equal

halves on the dorsal surface, and at least a shallow furrow is

always present. The sensilhe are normal and on ((2.

VIII is quadriannulate. .41 is slightly wider than YII a 3,

and like the latter shows a partial division into the secondary

annuli. .42 bears the sensilhe and « 3 is completely divided

into b 5 and d 6, each of which equals a 2 in size.

The series of complete quinqueannulate somites begins

with IX and ends with XXIII, making 15 in all. The five

annuli of each of these are of equal length. The sensillae are

small but very conspicuous on properly prepared material

;

but the exact size of the sensory areas is difficult to figure, as

they appear as circular white spots, in small unpigmented

areas the limits of which are rather vaguely defined. All of

the sensillffi are much subject to variation, even the dorso-

medians and dorso-laterals being frequently subdivided,

changed in position, or entirely wanting. But the two

marginal series are especially prone to subdivision ; and they

are very commonly represented by a chain of contiguous

smaller sensory areas, not infrequently made up of four or

five members.



524 Illinois State Laboratory of Natural History.

Somite XXIV is quadriannulate, but it is the posterior

end (a 3) which is least developed, instead of the anterior

end (al) as in the quadriannulate somite VIII. In some

examples the large posterior annulus (rt3) is marked by a

slight furrow, which is more frequent on the ventral surface.

XXV. Because of its variations this normally triannulate

somite is one of the most interesting. A 1 is always longer

than XXIV a 3. In four specimens it exhibits no trace of a

subdivision dorsally or ventrally ; in six there is more or less

evidence of a ventral furrow ; four examples, while lacking

any trace of a furrow, show two distinct integumental ridges

at the margins of this annulus ; two others have both the

marginal ridges and the furrow ; and in one individual of

large size the furrow extends even half way around the dorsal

side. The remaining annuli a 2 and a 3 are of equal size

and present no noteworthy features.

XXVI is uniannulate above, and the sensillse, with the

exception of the dorso-median, which are at about the middle

of its length, are situated close to the posterior border. On

the ventral side a partial annulus is developed in many cases

posterior to the line of sensillae.

XXVII. For the reason just stated the short preanal

annulus is regarded as XXVII al, while a '2, and a 3 are

united in a single sensilliferous annulus which is cut into

by the anus. The furrow ft 1/a 2 is sometimes incomplete

mesially.

The dorsal surface of the sucker is marked by a variable

number of concentric furrows crossed and connected by

irregular wrinkles. The sensillse are difficult to distinguish,

but generally about three belonging to each of the dorsal

series are present.

Reproductive Organs.—The dissection represented in the

figure (PL XLV., Fig. 26) was made upon a well-extended

mature specimen of medium size. In this the nerve cord

passes to the right side of both the genital orifices, and the

unpaired portions of the genital ducts lie to its left. The

dissection of a number of specimens of this species from

several localities shows that while this relation between the



The Hirudinea of Illinois. 525

nerve cord and the genital apparatus usually obtains, it is

not constant and diagnostic of the species. Cases have been

found in which the nerve cord passes to the left of the genital

exits or to the right of one and the left of the other, or in

which the atrium or vagina crosses the nerve cord dorsally

and lies partly on each side of it.

Ten pairs of testes (tl, td), belonging to somites XIV to

XXIII inclusive, appear to be constant. Each occupies

the first two annuli of its somite and the posterior

annulus, or even two annuli, of the preceding somite. They
are largest in the middle of the series, and become smaller

toward both ends. The twenty short vasa efferentia are simi-

lar in structure and appearance to the paired vasa deferentia

into which they empty. Each of the latter (lul) is a rather

conspicuous glandular tube of yellowish color which takes a

more or less sinuous course just entad of the line of nephridial

vesicles. When about opposite to the male pore it turns

sharply caudad, having become narrower and of firmer, less

glandular, texture, and soon passes into a much convoluted

region, the epididymis (ej)). The latter is neither compact
nor massive, and in the posterior part of XIII opens into the

sperm sac (ss), a fusiform enlargement with which the ductus

ejaculatorius (de) begins. Throughout its greater part the

latter is a delicate tube which extends forward to a point

opposite to the male pore and then again bends on itself

sharply caudad to open into the fundus of the atrium or

penial sheath {at) at the anterior limit of somite XV.
Throughout its entire length the ductus ejaculatorius has

firm glistening muscular walls. Generally the right ductus

passes beneath the nerve cord at its anterior turning point

behind ganglion XI, but occasionally it is the left which

makes this crossing.

The atrium or penis sheath (at) is very long and slender.

Beginning at the anterior end of somite XV it reaches caudad

to ganglion XVII, bends sharply on itself, and passes directly

cephalad to the male orifice. In the specimen figured, which

measures 92 mm. in total length, the atrium has a length of

40 mm., the ratio between the short and long limbs being as



526 Illinois State Laboratory of Natural History.

1 to 2.3. The organ is of firm consistency and very mus-

cular. In shape it is terete with the closed end slightly

enlarged and provided with an ensheathing layer of prostate

glands (^i>). The protruded penis is a long filiform organ

reaching a length of at least 30 mm., though this condition

is not exhibited by any of the Illinois examples.

The female organs are equally and correspondingly special-

ized. A pair of ovaries (or) lie on the 2d pair of testes

dorsal to the nerve cord and in the posterior end of XIV.

Yery short oviducts pass from them to a common meeting

place, where they are enveloped by the large glandula albu-

ginea (ga), from which the common oviduct emerges. This

narrow hrm-walled tube (ode) leads to a large pyriform

ovisac (os), which it joins a short distance from the extremity

of the narrow end. The vagina (va) begins near the large

end of the ovisac at the posterior end of somite XVI. It is

long, slender, and terete, about 2-3 times the diameter of the

common oviduct, of an appearance similar to the latter, and

with muscular walls. The coil and whorls into which it is

thrown are sufl&cient to give it, when straightened out, a total

length equal to the penis sheath.

Alimentary Canal.—The lip is separated by a slight circular

sulcus and fold from the three jaws. Each of the latter is

the anterior termination of a pharyngeal fold which here

becomes slightly more prominent and curves peripherally into

a little pocket into which the jaw may be retracted, so that

the whole tooth-bearing ridge may be concealed. The jaws

are low and rounded, not at all compressed on the free edge

and very little prominent. They bear a double file of

large coarse teeth (PL XLIL, Fig. 7) arranged in from

12 to 16 pairs. The individual denticles have bilobed

bases and sharp, slightly hooked,' apices, those of each

pair meeting in a common ridge above the groove which

separates their bases. From each side of the pharyngeal folds,

which continue the jaws caudad, somewhat lower folds arise,

and in the intervals between these three triad systems addi-

tional single or double folds may arise. Thus the pharynx

is thrown into from nine to twelve, or even more, longitudinal



The Hirudinca of Illinois. 527

ridges extending throughout its entire length. The pharynx

reaches into somite X.

A long narrow straight stomach reaches to XIX, where a

pair of large lateral cfeca arise and pass caudad to XXII or

XXIII. Along the course of the stomach are numerous
small lateral caeca, as many as two or three pairs per somite

;

and just posterior to the origin of the large posterior pair are

two or three pairs of quite large, short, globular caeca which

extend laterad dorsal to the principal ca^ca.

Color.—Many color varieties of this species occur, some of

which have been indicated by Yerrill ('74) ; but only the

blotched kinds are represented in the Illinois collection-

During life the ground color in such is generally some shade

of olive-green or greenish brown, blotched with irregular

intermixed spots of lighter grays and darker browns and

black. The former kind are likely to predominate on the

ventral side, from which the darker pigments may be alto-

gether absent. The darker markings may be scattered and
distant or so close as to become confluent and give to the

animal an almost black color. Most of the Illinois examples

are only moderately blotched. Preservation always causes

the loss of the green pigments. No metameric features have

been detected in the pigmentation of this species, nor is there

any evident close relation between the disposition of the pig-

ment and the arrangement of the muscles.

Habits.—In the neighborhood of Philadelphia this so-

called horse-leech lives in the mud by the sides of pools,

ditches, and streams. At times it leaves the water in search

of earthworms, which constitute part of its food. Various

kinds of aquatic insects and their larvae, aquatic oligochaetes,

gastropods, and lamellibranchs are eagerly eaten, and large

quantities of mud containing organic matter are swallowed.

When the opportunity arises this leech will take blood,

attaching itself to drinking cattle or to the legs of boys

wading in its haunts.



528 Illinois State Lahoratory of Natural History.

Hsemopis lateralis (Say),

Hirudo lateralis Say ('24).

Mncrobdella valdiviana Philippi ('72).

Semiscolex terrestris Forbes ('90).

Diagnosis.—VII d 5 and d 6 and VIII d 1 and d 2 are fully

developed, so that VII is quadriannulate and VIII quinque-

annulate. The male pore is on annulus 34 (XI ^6), the

female on 39 (XII l? 6) ; the vagina and atrium extend to the

anterior part of XIV; the ovaries lie between the female

pore and ganglion XII.

General Description.—Many of the characters of this large

leech have been described by Forbes ('90). It reaches a size

much larger than H. marmoratis, some examples of the

terrestrial variety from Illinois measuring as contracted

alcoholic specimens nearly 8 in. in length and f in. wide.

The smallest specimen in the collection measures 38 mm.,
the largest 190 mm., in length. A medium-sized individual

from which the drawings were made, measures :
—

mm.
Total length, . . . . . . . 103.
Length to cf pore, . . . . . .21.
Width at & pore, 10.5
Greatest width (just anterior to 17th nephridiopore), 13.5
Width at anus, . ..... about 5

.

Diameter of posterior sucker, . . . . 6.

Depth at d pore, ..... about 4

.

Depth at_ last nephridiopore, . . . . 5.5
Depth at anus, . . . . . , 2.5

Living aquatic examples which I have watched assume the

attitudes and shapes described for H. marmoratis, but

H. lateralis is much more slender and capable of much
greater elongation. The greatest width is further back
(about XXIII), from which point the body tapers gently

forward. Compared with H. mar)noratis the ventral surface

seems flatter, the dorsal more abruptly, but still gently,

arched, and the anterior region more terete. As in that

species the surface of the body is perfectly smooth, without



IVic Hirudnwa of Illinois. 529

any papilhi?, but unlike that species the metameric sensillse

are exceedingly difficult to detect, and I am not yet satisfied

that they have been correctly identified in surface views. A
better developed muscular system gives the body of this

species a somewhat firmer consistency.

The ammli (PI. XLVL, Fig. 28-32) are remarkably

distinct, which results chiefly from the presence on each of a

strong welt or ridge which encircles it and causes the margins

to stand out like so many serra?. Just anterior to the ridge

a faint furrow appears on many of the secondary annuli.

The upper lip (PL XLVL, Fig. 29, 32) is rather slender

and pointed and its ventral surface divided by a slight

median and several lateral longitudinal grooves. The mouth
and sucker are relatively smaller than in the horse-leech. A
slight constriction is usually evident between the fourth and

fifth pairs of eyes. The eyes (Fig. 28) are arranged as in

//. marmoratis.

Very few examples exhibit a well developed clitellum, but

when present it has a form and extent similar to that of

H. marmoratis. Although the male and female pores are

situated on the annuli homologous to those bearing them in

H. marmoratis, two more annuli intervene between them and

the anterior end than in that species. This results from the

presence of an additional annulus in each of somites VII and

VIII. The orifices are also situated further caudad on their

respective annuli (though seldom beyond the middle) than in

that species.

The usual seventeen pairs of nephridiopores (PI. XLVL,
Fig. 29) are situated on the annulus d'2 of somites VIII to

XXIV inclusive. As in H. marmoratis they open just pos-

terior to the transverse ridges, which at each pore are pushed

forward as short spout-like projections which may serve to

direct the flow of the excreted fluid. The distance separating

the two pores of a pair is almost exactly half the width of the

body at that point.

Annuli and Somites.—Owing to its distinctness the annula-

tion (PI. XLVL, Fig. 28-32) is very easy to work out, but

on account of the difficulty or impossibility of detecting the



630 Illinois State Lahoratorij of Natural History.

metameric sensillae in surface views the metamerism is less

readily determined. Comparison with H. marmoratis brings

to light some interesting points of distinction between the

two species. No differences of anj^ consequence are notice-

able in the first five somites.

In VI, «3 is relatively much longer, and occasionally a

faint subdivision appears on its dorsal surface.

VII presents a similar condition in al, while « 3 is repre-

sented by the fully developed secondary annuli d 5 and d 6,

w^hich are completely separated both dorsally and ventrally,

making this somite quadriannulate, with the formula

al+a^+d5+ d(), or idl-{-d2)-\-a2+d 5+d 6.

VIII is quinqueannulate, owing to the complete separa-

tion of (^1 and d2. This species presents, therefore, one

more complete somite—having the formula I? l-\-d 2-\-a'2,-\-

^ 5-i-d 6—than does H. marmoratis.

In most of the complete somites, usually from about X to

XXI, a characteristic relative size of the component annuli

is maintained. yl2 is always the shortest, bl and b'^ are

equal and slightly longer, and b 5 and b 6 are equal and still

longer. The faint depressed line which is mentioned above

as crossing most of the annuli is rarely discernible on a 2,

while on the secondary annuli it is usually quite evident.

In XXIV, which is the last complete somite, the relative

size of the annuli anterior and posterior to the neural annulus

(«2) is reversed, bl and b'^ being larger than b5 and b&.

XXV is triannulate, a 3 being distinctly smaller than a 1

or « 2, especially on the ventral side, where it becomes some-

what approximated to a 2 and the dividing furrow less deep.

XXVI is biannulate, the first annulus being dorsally as long

as the second at the margins, or even longer, but relatively

smaller mesially. By displacing the sucker the second ring is

seen to include on each side a remnant of a very narrow

posterior ring, which in one specimen is well developed both

dorsally and ventrally. As the supposed sensillae are found

on the anterior part of the second ring this is regarded as

representing ^2 and ^3.

XXVII is biannulate and includes the anus.



The H'lrudinca of Illinois. 531

Fortunately, in the posterior region of some aquatic indi-

viduals from Ohio the sensilla? are comparatively distinct, so

that the determination of the values of the annuli and of the

limits of the somites is accomplished with greater ease and
confidence than would otherwise be possible.

Reproductive Onians.—The reproductive organs also have

been described by Forbes, to whose account a few notes may
be added. The nerve cord may pass to the right of the

genital exits, as described by Forbes, or to the left, as here

figured. In two out of three dissections the latter condition

prevailed ; but the number is of course insufficient to

determine which is the more usual.

The figure (PI. XLY., Fig. 27) will serve to show the

marked contrast in several respects between these organs in

H. lateralis and H. niarmoratis, in most of which the former

approaches nearer to the H. sanguisuga of Europe. The
sperm-sacs (ss) and epididymes {ep) of H. lateralis are con-

fined to the distance between ganglia XI and XII, and the

latter are massive and compact and closely molded around

the sperm-sacs. The atrium {at) of this species is much
shorter, its posterior turn being at ganglion XIV ; the relative

lengths of the short to the long limb is as 1 to 1.7. The
penis is not protruded in any of the Illinois specimens, but

in the aquatic variety from Ohio is essentially similar to

that of H. marmoratis.

Unlike the latter species the ovaries (oi-) of this are situated

far in advance of the second pair of testes. Sometimes, at

least, they lie beneath the nerve cord and between the female

exit and ganglion XII. Similarly to the atrium, the vagina

is relatively short and never extends posterior to ganglion XIY.
Alimentary Canal.—Counting the rudimentary denticles

which complete the series posteriorly the number on each

jaw is from 20 to 25 pairs (PI. XLV., Fig. 25), arranged,

as in H. marmoratis, in two contiguous series. They
are of more irregular shape than in that species and of

smaller size, but their greater number causes them to occupy

an approximately equal distance on the jaws.

Color.—Forbes ('90) has described the colors from living



532 Illinois State Lahorntory of Natural History.

specimens of the terrestrial variety. On living aquatic ex-

amples from Ohio the dorsal black stripe may be conspicu-

ous, but is more frequently faint and obscure, broken into

small spots, or totally wanting.

Habits.—The habits of this species have been briefly

described by Say ('24) and Forbes ('90).

HERPOBDELiLIDiE.

*ERP0BDELLA BlaINVILLE.

Erpobdella punctata (Leidy).

Nephelis punctata Leidy ('70).

Nex)helis lateralis Bristol (in part) ('98).

It has been found impossible to certainly identify this with

any of Yerrill's species. There is little doubt that Nephelis

lateralis Verrill and Nephelis quadristriata Verrill are founded

on two distinct species which are common in New Eng-

land and both of which are quite distinct from Leidy's

species ; but N. quadristriata Verrill (not Grube) may be in

part synonymous with E. punctata.

Diagnosis.—Complete somites quinqueannulate, b 6 some-

times slightly larger than the other annuli but not typically

divided in the middle by a cross-furrow
;
pigmented eyes three

pairs, the first situated on II, the second and third on IV

;

genital orifices, male at XII blja^, female at XII b 5/d 6;

atrium deeply cleft, the prostate cornua prominent, and the

anterior loops of the vasa deferentia reaching to ganglion XI.

General Description.—Bristol ('98) has given an excellent

description of the external characters, the annulation, and the

neural metamerism of this species, most of which need not be

repeated, especially as the external features distinguishing

species of this family are mostly slight and obscure. The
number and arrangement of the external annuli may be

*Blainville's original spelling is liere followed, lilanchard has changed this to
Herpobdella, and separated the family from the Hirudinidie.



The Hirudinca of Illinois. 533

almost exactly the same in several species, which are never-

theless readily distinguished by other and very obvious char-

acters, and especially by the terminal portion of the male
genital ducts.

Erpohdella punctata reaches a large size and has a more
robust form than any other of our common nephelids. In

preserved specimens the dorsal surface is rougher and the

posterior lateral margins thinner than in most other species.

The body is very muscular and has a firm feel.

For the purpose of comparison Avith the species of Dina
which are described below some features of the complete

somites may be mentioned. Of these there are seventeen,

VIII to XXIY inclusive. All of the live annuli are of

nearly equal size, but i^" 6 is frequently slightly enlarged.

This is, however, never very obvious, and the annulus is

never marked by a transverse furrow except in strongly con-

tracted specimens in which all of the annuli are equally

affected. A'2 is noteworthy as being rougher than the

secondary annuli, and its papilhe are frequently larger and

more numerous, extend further marginally, and are more

subject to concrescence into a transverse ridge. When fully

extended all of the annuli are free from cross-furrows or

wrinkles, but w'lien contracted irregular and interrupted

transverse furrows may appear on all of the annuli. These

may occur anterior to the papillae only, or both anterior and
posterior, in w^hich latter case the anuvilus is more or less

completely divided into three parts, of which the middle bears

the principal papillae.- Such transient subdivisions must not

be mistaken for the true tertiary annuli which appear in

Dina, etc.

Reproductive Organs.—The external male organ when fully

extruded has the form of a low circular disc occupying nearly

the entire median width of two annuli. It consists of a

marginal rim fitting closely around a transverse elliptical

central cushion of al)out twice the height of the rim. The
terminal openings of the sperm-ducts appear well separated

on the sides of the cushion.

The testes extend through six and one half somites



534 Illinois State Laboratory of Natural History.

(posterior part of XYIII to the anterior part of XXIY). In

one specimen in which they were counted the number varied

from fifty to sixty on each side of each somite. They are

small pyriform or globoid bodies grouped about the vas

deferens, into which they empty, in most cases by separate

ducts. The vas deferens (PL XLVIL, Fig. 35, vd) is an

extremely fine, straight tube reaching to ganglion XVIII.

At this point the duct suddenly enlarges into a very conspic-

uous epididymis or sperm-sac (ss). This much convoluted

tube continues through several somites but gradually dimin-

ishes in diameter. By somite XV it has become only one

half or one third of its greatest size, and in XI\' the convo-

lutions become more open and soon the duct is merely wavy.

This region is the ductus ejaculatorius (de), which passes

forward in a long loop to ganglion XI, at which point it

turns sharply mesiad and caudad and returns to the terminal

organ. Eegarding all of the latter as the atrium, it consists

of two more or less elongated curved conical horns (j))

directed longitudinally. At their bases they rest on a pair of

swollen pedestals covered with a layer of prostate glands,

which also extend somewhat on to the bases of the cornua

themselves. This basal region, the two halves of which

embrace the nerve cord between them, may be separated

quite to the basal integuments, where each half communicates

by a separate orifice with a small bursa. The median part

of the atrium appears to be represented by these two basal

halves of the cornua.

The ovaries (PI. XLVIL, Fig. 35, ov) are a pair of long

slender sacs, each doubled on itself, with both ends in somite

XII, and the loop reaching far back along the median line,

ventral to the alimentary canal, to the neighborhood of

ganglion XVII. From somite XIV to somite X^'II the two

ovarian sacs lie side by side; just anterior to ganglion XIV
they diverge, the closed end of each arching upwards around

the pharynx ; and they end close together, near the median

line. The external ends of each, on the other hand, retain

their ventral position and join beneath the nerve cord at the

common external opening ( ? ).



The Ilirudinca of lU'inois. 535

Hahits.—The favorite food of this species is small aquatic

oligochittes. Bristol ('98) and Leidy ('70) have given some
account of its habits.

DiNA E. Blanchard.

Dina fervida (Yerrill).

Xtphelis fervida Verrill ('74).

Nejihelis fervida is supposed to have been described from

individuals of this species having eight eyes, a variation

which frequently occurs. The species here described is

abundant in the Lake region from which Verrill's types were

taken, and has the size, form, and color of that species.

Diagnosis.—Complet esomites quinqueannulate, d 6 being

distinctly enlarged and divided by a cross-furrow into two

equal halves
;
pigmented eyes normally three pairs, the first

situated on III
;
genital orifices at XII d 2[a 2 and XII h bjbQ;

median chamber of atrium of medium size and not deeply

cleft, the prostate cornua prominent, and the vasa deferentia

not reaching anterior to their ends in somite XII.

General Description.—A single small specimen represents

this species in the Illinois collections, and the following notes

are derived from numerous examples in my own collection

received from Ohio and Michigan and from the well-preserved

series taken by Professor Eeighard during his recent explo-

ration of Lake Erie.

None of the large number of specimens examined reaches

a length of much more than two inches. The body is

depressed posteriorly ; the mouth is relatively large and the

lip blunt. The posterior sucker is relatively larger ihan in

most small nephelids, with its anterior margin more broadly

free and reaching as far forward as XXV ^2. The body is

not of particularly firm consistency. The clitellum extends

over fifteen annuli, X b 6 to XIII a'i.

The annulation and metamerism are essentially as in

E. punctata, except that the first pair of eyes is placed on

the third instead of the second annulus, and that in the com-



.536 Illinois State Laboratory of Natural History.

plete somites /^ 6 is subdivided. In addition to these there

are some incipient differences, but they are too minute to be

used in this connection. The larger size and subdivision of

the annulus ^ 6 is a very obvious and constant character. It

is true that many of the other annuli at times show faint

cross-furrows, but these lack the constancy, depth, and com-

pleteness of the diagnostic one.

Reproductive Organs.—The testes are larger and fewer than

in E. punctata. In on^ specimen they average thirty-two to

each side of each somite. As in that species, they extend

from the posterior part of. XVIII to XXIV, The vasa defer-

entia (vd), sperm-sacs (ss), and the greater part of the ducti

ejaculatorii {de, PI. XLVIL, Fig. 36) exhibit no important

differences ; but the anterior ends of the latter stop short at

the anterior limit of somite XII, where they join the apical

ends of the prostate cornua. When the copulatory organ is

fully retracted the ducti form no loops whatever anterior to

these cornua ; but when it is protruded the latter are drawn

somewhat caudad, leaving a short sweep of the ductus

anterior to it on each side. The prostate cornua (p), though

prominent, are shorter than in E. punctata and diverge more

widely laterally. A third important difference is found in

the presence of a well-developed median atrial chamber {at).

This is quite undivided in the median line, where the nerve

cord, instead of sinking between two separated lobes, is raised

some distance above the body floor. The prostate glands

cover the dorsal portion of this chamber as well as the bases

of the prostate cornua.

The protruded male copulatory organ differs in some

details from that of E. p)unctata. It is relatively larger and

especially higher. It is supported on a broad pedicle which

projects freely through the male pore. Around the entire

edge of the disc is a groove which divides it into a proximal

and distal circular ridge. The latter bears a delicate ring-

like flange which probably corresponds to the muscular

border here present in E. jnmctata. The central cushion is

subcircular, and instead of two widely separated openings has



The Jlirudinca of Illinois. 537

a single large crescentic one, into the deep ends of which the

prostate cornua open.

The female organs present no important differential char-

acters, although the ovaries (ov) of all of the specimens dis-

sected reached to ganglion X\'III.

Color.—Living specimens, according to Verrill's description

and a water-color sketch sent me by Professor Eeighard, are

pale red with some darker cloudings.

Preserved specimens may be separated into two groups

according to the amount of pigment present. One group,

which includes the smaller and a portion of the larger ones,

lacks pigment entirely ; the other, which includes most of the

larger examples, has the dorsal svirface marked with more or

less numerous minute black flecks which differ greatly in

number and somewhat in arrangement. Many specimens

have so little pigment as to appear light-colored, with a faint

dark band on either side of a median clear band ; in others

the dark bands are very broad ; and still others appear quite

dark, the pigment specks being very numerous and close and
extending continuously over the median region. In all cases

the margins, including the region of the lateral vessels, are

unpigmented ; and in no case does the pigment assume any
other form than that of minute flecks more or less closely

placed.

Dina microstoma sp. nov.

Diagnosis.— Complete somites quinqueannulate, ^6 en-

larged and subdivided ; first pair of eyes in III ; male orifice

at XII d ^ja 2, female orifice at XII/XIII ; median chamber of

atrium relatively large and without median groove
;
prostate

cornua inconspicuous, shorter than diameter of median

chamber ; vasa deferentia lacking anterior loop and ending

abruptly at the atrium.

General Description.—This is a generally slender species.

Well-preserved specimens are nearly terete and in extension

linear. An average specimen measures :

—



538 lUinois State Laboratory of Natural History.

mm.
Total length, 42.

Length to male pore, . . . . . .10.
Width at male pore, . . . . . . 3.4

Greatest width (middle), . . . , .4.2
Width at anus, ..... 3.5

Depth at male pore, .... about 1 .

5

Depth at middle, ..... about 2

.

Depth at anus, . . . . . . .1.2
Diameter of posterior sucker, . . . . 2.5

The width is greatest at about the middle of the body but

varies little in the entire postc-litellal region. The margins of

the body are rounded except just about the anal region,

where lateral flanges begin at about XXIII and become

more and more prominent until they terminate in a pair

of thin expansions which embrace the base of the sucker. A
curious feature which appears in a great many specimens

is a short contracted region just behind the clitellum, where

the body becomes perfectly terete and bellies ventralward.

From the genital region forward the body tapers quite rapidly

to a point just posterior to the mouth and then rapidly con-

tracts into the narrow lip. As in nephelids generally, the

entire body is covered w^ith small sensory papillae arranged

in zones on every annulus.

The mouth is small, even in specimens which have been

killed in a much relaxed condition. In most specimens the

upper lip is extended, slender, and prominent, and is often

most sharply distinguished from the succeeding annuli by a

deep furrow which passes behind the postoral ring. Dorsally

it is smooth, divided into distinct but very narrow rings, and

provided around the margins very richly and above sparingly

with labial sense organs.

There are three pairs of eyes, of which the first are the

largest and are situated on somite III, instead of on II as in

most nephelids. Sometimes one or each of these is repre-

sented by two. The second and third pairs are on IV, the

dorsalmost slightly in advance.



'The llirudinea of Illinois. 539

The male gonopore is situated as usual at XII d'2ja2, the

female at XII; XI II, three aimuli consequently intervening.

The former is a large and conspicuous opening usually sur-

rounded by a thin integumental disc which spreads over

about one half of the contiguous annuli. The female pore is

small and usually concealed. A strongly developed clitellum

is generally present. It is thick both dorsally and ventrally,

sharply defined, and extends over fifteen annuli, from X ^ 5

to XIII d2. The nephridiopores are as usual.

Even for a nephelid the posterior sucker is weak and small.

It is very broadly attached, with scarcely any free margin

anteriorly, where it reaches only as far forward as XX\.I.

Eight low radiating ridges or lines of papillit disposed in

pairs mark its upper surface. Anus large, with a much
wrinkled margin, XXVI/XXMI.
Annuli and Somites.—^The external features of metamerism

in this species differ but little from those of E. punctata,

but as Bristol has adopted another standard of enumera-

tion in his description of that species it seems best to give a

brief account of the present species.

I is the wide anterior region of the lip.

II is a narrow preocular annulus bearing one row of sen-

sory papilla'.

III is a single wide annulus faintly subdivided and bearing

a complete row of sense organs posteriorly and an incomplete

row anteriorly. The large pair of eyes are on its extreme

anterior part and are separated by a distance of about three

times their width.

I\' is biannulate, the first ring being distinctly subdivided

and separated from the second dorsally but united to it ven-

trally. In many cases its posterior furrow is very deep and

limits the head region as noted above. The second group of

eyes is borne by this somite, the ventral pair being on the

furrow a 2ja 3, the dorsal just in advance of it.

V is also biannulate, the first annulus bearing two rows of

sense organs and being somewhat wider than the second.

\'I is triannulate. .41 and a 3 are each slightly wider than



540 Illinois State Laboratory of Natural History.

a 2, bear two rows of sense organs, and are faintly divided

marginally.

\l\ is quadriannulate, the fourth annnlus being double

;

but as none of the other annuli show any indication of further

division the formula is regarded as h 1+6 2+a 2-|-(6 5+6 6).

VIII to XXIII inclusive are complete somites. In these

the relative widths of the annuli and the subdivision of 6 6

are not such constant and obvious features as in Dina fervida,

but careful measurements of a large number of cases show
the approximate equality of the first four annuli, while 6 6

proves to be about twenty per cent, larger. In many of the

best-preserved specimens this relative proportion appears

with great constancy and regularity, but in others is more or

less obscured. In well-extended specimens a dividing furrow

cuts 6 6 approximately into two equal sub-rings, but in con-

tracted examples this is also obscured by the development of

transient wrinkles as described for E. punctata. Of the more
distinct sensory papillae there are on each ring from fourteen

to eighteen above and about an equal number of smaller

ones below. These are arranged in an irregular transverse

row along which smaller sense organs are scattered.

Frequently a median longitudinal dorsal tract is entirely free

from them, and they always become more evident marginally.

On o 2 the papillae are usually more prominent, especially so,

as Bristol has observed, on some of the posterior somites.

On 6 6 two rows of papillae appear. These are especially

distinct at the margins of large individuals.

XXIV is sometimes complete, and is always quinque-

annulate so far as observed. In most cases it differs from
the complete somites only in the relatively smaller size of 6 6

and the tendency, sometimes quite evident, for 6 5 and 6 6 to

unite on the ventral side.

XXV is usually quadriannulate, sometimes only tri-

annulate, but it has been found impossible to find any in-

herent clue to the exact values of the annuli. Analogy with

other species would point to the first form as being composed
of 6 1+6 2+c 2+a 3 ; the second, of a 1+a 2+a 3.

XXVI is biannulate, the wide anterior annulus showing



The irn-ud'uica of Illinois. 541

two rows of papillne. The amis cuts the second, w'hich bears

but very few papillae. XX\'II is postanal and biannulate.

liepwductire Organs.—The numerous small testes are found

in somites XVIII to XXIII, bat their number was not deter-

mined. The vasa deferentia, sperm-sacs, and ducti ejacula-

torii are sufficiently indicated in the figure (PL XLVIL,
Fig, 37). The latter end abruptly, without any preatrial

loop whatever, at the prostate horns, into the ends of which

they empty.

The atrium is a very characteristic one and differs from

that of any other species of American nephelid which I have

examined. It may be remarked in passing that the efferent

male apparatus of this species and TJinn fervida have many
characters in common which distinguish them from D.viexi-

C(ina Duges, which Blanchard regards as being co-specific

with the type of the genus. The median chamber (at) is a

thick-walled sac of relatively large size. It stands up promi-

nently from the body floor, raising the nerve cord with it and

barely marked by a median groove. Its transverse diameter

is much greater than the antero-posterior and about equal to

its height, but in immature specimens the organ is spherical.

The prostate cornua (p) are small,—when straightened,

less than the shortest diameter of the median chamber,—and

their attachments are far apart on the dorsal surface of this

chamber, with which they remain in close contact as they

curve strongly ventrad on each side. At their lowest point

at the sides they become continuous with the ducti ejacu-

latorii as above described.

The ovaries (or) present no peculiar features, and their form

and relations are sufficiently indicated in the figure.

Color.—Not one of many examples of both young and old

shows any pigment. This would indicate that during life

they are red, the color of the blood showing through the

integuments.

Small tubificid worms have been found in the stomachs of

those examined.



542 Illinois State Laboratorij of Natural History.

Note on Discodrilidce.—The collection sent me includes

three hottles of DiscodriluUe comprising altogether about

sixty specimens of Bdellodrilus jiliiladelphicus (Leidy) Moore.

This species was originally described by Leidy under the

name of Astacohdella pluladelphica in the Proceedings of the

Philadelphia Academy of Sciences for 1851, page 209.

Some additional notes on it may be found in two papers by

Moore in the "Journal of Morphology," Vol. X., page 498,

and Vol. XIII., page 327 et seq. The Illinois specimens were

taken from the exterior of Cambarm diogenes and C. hlan-

dingii.

University of Pennsylvania, August,- 1900.



The H'lrudiiua of Illinois. 543

BIBLIOGEAPHY.

Apathy, Stefan.

'88. Analyse der iiusseren Kdrperform der Hirudineen. Mittbeil.

Zool. Ststion Neapel. Bd. VHI., pp. 153-232.

Blanchard, Emile.

'49. Gay's Historia fisioa y politica de Chile. Zoologia, Tomo III.,

pp. 43-50. Paris.
•

Blanchard, Raphael.
'92. Description de la Glossiphonia sexoculata (Bergmann). Bull,

Soc. Zool. de France, Vol. XVII., pp. 178-182.

'96. Hirudinees de la Prusse Orientale. Bull. Soc. Zool. de France.

Vol.XXI., pp. 118-120.

'96a. Viaggio del dott. A. Borelli nella Republica Argentina e nel

Paraguay, Hirudinees. Boll. Mus. Zool. Anat. comp. R. Fniv. di

Torino, Vol. XI., X. 263, pp. 1-24.

Bristol, C. L.

'98. The Metamerism of Xephelis. Journ. Morph., Vol. XV., pp.

17-72.

Brooks, W. K.
'82. Handbook of Invertel)rate Zoology, pp. 160-167. Boston.

Castle, W. E.

1900. The Metamerism of the Hirudinea. Proc. Amer. Acad. Arts

and Sciences, Vol. XXXV., pp. 285-303.

Forbes, S. A.

'90. An American Terrestrial Leech. Bull. 111. State Lab. Nat.

Hist., Vol. III., pp. 119-122.

Graf, Arnold.
'99. Hirudineenstudien. Abb. der Kaiserl. Leop.-Carol. Deutschen

Akad. der Naturf.. Bd. LXXIL, pp. 213-404.

Leidy, Joseph.

'68. Xotice of some American Leeches. Proc. Acad. Nat. Sci.

Phila., 1868, pp. 229, 230.

'70. Description of Nephelis punctata. Proc. Acad. Nat. Sci. Phila..

1870, p. 89.

Moore, J. Percy.

'98. The Leeches of the U. S. National Museum. Proc. U. S. Nat.

Mus., Vol. XXL, pp. 543-563.



544 Illinois State Laboratory of Natural History.

1900. A Description of Microbdellabiannulata with especial regard

to tlie Constitution of the Leech Somite. Proc. Acad. Nat. Sci.

Phila., 1900. pp. 50-73.

Moquin-Tandon, A.

'46. Monographic de la famille des Hirudin^es. Paris, 2d ed., 1846.

Philippi, R. A.
'72. Macrobdella,ein neues Geschlecht der Hirudineen. Zeitscb. fiir

die gesammt. Naturwiss. {2\ Bd. VI., pp. 439-442.

Say, Thomas.
'24. Narrative of Expedition to the Source of the St. Peter's Elver,.

etc., Vol. II., Appendix, pp. 266-268. Philadelphia.

Verrill, A. E.

'74. Synopsis of the North American Fresh-water Leeches. Rep.

U. S. Comra. of Fish and Fisheries for 1872-73, pp. 666-689.

Whitman, C. O.

'86. The Leeches of Japan. Quar. Journ. Micr. Sci., Vol. XXVI.,

pp. 317-416.

'92. The Metamerism of Clepaine. Festschr. zur 70 ten Geburtstage

R. Leuckart's, 1892, pp. 385-395.



The Ilirudinea of Illinoh. 545

EXPLANATION OF PLATES.

The somites and ganglia are indicated by Roman numerals 1 to

XXVII; and the annuli of individual somites by letters (o, b, etc.)

which indicate the successive generations by which they multiply from

the triannulate type, the indices (1, 2, etc.) being their theoretical uum
ber in an antero-posterior series.

With the exception of a few modifications which are explained in the

text the lettering is uniform for all of the figures.

The metameric seusilhe: md, dorso-median: lU, dorso-lateral; dm,

dorso-marginal; sm, supra-marginal; sbm, sub-marginal; rl, ventro-

lateral; vm, ventro-median.

The cutaneous papillse: mp, median; mdp, dorso-median; dip, dorso

lateral; dmj), dorso-marginal; smp, supra-marginal.

General: a, anus; at, median atrium or penis sheath: atf, internal

elevation resulting from male pit (false atrium', covered by a layer of

copulatory and prostate glands; n(i, lumenal coat and sac of atrium; c,

clitellum; cffi, copulatorj' glands; cgp, copulatory gland pores, c^of
male and 9 of female system; de, ductus ejaculatorius (variously modi-

fied and not always strictly homologous as indicated in the several

figures); ej), epididymis (remark under de applies to this also); g,

cutaneous glands; g XI to XVIII, ganglia of the ventral chain, num-
bered to agree with their somites; gp, (or pg), prostate glands and pros-

tate region of penial sheath; ga, glandula albuginea; np 1 to 17,

nephridial openings of pairs indicated by the numerals; od, oviduct;

ode, common oviduct; of, closed end of ovarian sac; os, ovisac (uterus);

01', ovary or ovarian sac; ov' (in Fig. 27), position of ovary: p, prostate

cornua of atrium; pg (or gp), prostate glands and prostate region of

penial sheath; ss, sperm-sac; t 1, 2, etc., testes, numbered by pairs

from before backwards; va, vagina; vd, vas deferens; (^,male genital

orifice or its position; $ , female genital orifice or its position.

Unless otherwise stated all of the figures are made from specimens in

the Illinois collection and have been copied to scale as nearly as possible

after the originals, which were drawn upon camera tracings. Diagrams
are indicated.

Plate XLIL
Fig. 1. Placohdella parasitica. Dorsal view showing the metam-

erism and annulation of the twelve anterior somites; the cutaneous

papillae are not indicated. The color pattern is shown, the stippled parts

being the brown or olive background and the plain areas the yellow

spots and band. X 5.

Fig. 2. Placohdella rugoaa. Similar representation of the anterior

ten somites (except X a 3). The principal cutaneous papillae are shown.

From a specimen taken near Philadelphia. X 5.



546 Illinois State Laboratory of Natural History.

Fig. 3. Placohdella rugosa. Details of papillation, etc., of the right

half of the dorsal surface of somite XIX of a large example. The lines

to the right indicate the relative positions of the ventral furrows. X 5.

Fig. 4. Placobdella parasitica. A similar view of onehalf of somite

XIX, but of a much smaller specimen, x 5.

Fig. 5. Hemiclepsis carinata. The principal features of the external

morphology of the dorsum of somites I to XII. Drawn mostly after a

specimen from Venice, Ohio, and very slightly diagrammatic, x 4. 5.

Fig. 6. Glossiphonia lineata. A slightly diagrammatic figure show-

ing the external morphology of the dorsum of somites I to X. The
annulation is originally derived from young; the sensillae and papillaj

added as determined in adults. The young, X 30.

Fig. 7. Hcemopis marmoratis. Surface view of denticles from median

jaw. X 112.

Plate XLIIL

Actinobdella inequiamiulata.

Fig. 8. The dorsal external morphology of the entire leech (somites

XIII to XXI) omitted. Somewhat diagrammatic in that the furrows

are made to appear more regular than in the original. X 35.

Fig. 9. Side view of the posterior end, showing the sucker with some

of its papillfe projecting. X 35.

Fig. 10. Outline of the sucker from below, with the circle of papilla?

somewhat diagrammatically shown. X 35.

Fig. 11. A small portion of the sucker rim showing the muscular ribs

and four of the papillae. The glandular ducts of the latter are stippled.

X 130.

Plate XLIV.

Philohdella gracile.

Fig. 12, 13. Dorsal and ventral views respectively of the anterior nine

somites, showing the chief features of external morphology. X 5.

Fig. 14, 15. Ventral and dorsal views respectively of the posterior

end of the body; the dark spots are outlined. X 5-

Fig. 16. The ventral surface of somites XII and XIII showing the

various features of the region of the genital orifices. A combination

drawing from several specimens, x 5.

Fig. 17. Reproductive organs dissected and partly displayed, x 4.

Fig. 18, 19. Posterior and anterior ends respectively from the left

side. X 5.

Fig. 20. Surface view of a posterior portion of the tooth series of the

median jaw with the outline of the jaw partly shown. X 56.

Fig. 21. Female reproductive organs dissected and viewed from the

right side. From the same dissection as figure 12. x 4.



Plate XLII.

mp wA dip dl dm „ Try ^^ ^^P ^^ i!"- ^li^-

Glossipiioxid.*; Hirudixid.*;.



Plate XLIII.

ACTIXOBDELLA IXEQUIAXNULATA.



Plate XLI\*.

Philobdella gracile, Mackohdei.la decora.



Plate XLY

H.-EMOPIS MARMORATIS, H. LATERALIS.



Tlate XL\

H^EMOPIS MARMORATIS, H. LATERALIS.



^J

Plate XIX U.



The Hinidi Ilea of Illinois. 547

Macrohdella dcroiut.

Fio. 22. The mule organs dissected and viewed from the right side.

The left sperm-duct has its natural position, the right has been displaced

upwards. The dotted line indicates the form of the atrium before the

removal of a layer of muscles and prostate glands, x 4.

Fkt. 23. The greater part of the reproductive organs dissected and
viewed from above. From a specimen from the Fulton Lakes, New
York. X 4.

Plate XLV.

Fici. 24. HiriitopLs iiiiinnorutiti. Diagram of the entire dorsal annula-

tion, showing also the sensilhe, eyes, etc. x 2.

Fiu. 25. Hccinopis lateralis. Surface view of denticles of median
jaw. X 112.

Fig. 26. liannnpis ittarmoratin. Reproductive organs dissected and

partly displayed in dorsal view. The female organs are shown nearly

in situ: the atrium with the left ductus ejaculatorius and epididymis has

been displaced far to the left and only a portion of the right ductus is

shown: three testes of the left side are included, x 3.5.

Fig. 27. Haimopls lateralis. Reproductive organs dissected and dis-

played as in figure 2(5. The ovaries and oviducts are displaced to the

left, but the proper position of the left ovary is indicated in outline {ov' ).

The atrium is withdrawn somewhat to the right and the epididymes and

ducti ejaculatorii of both sides are shown, as well as the anterior end of

the right vas deferens and the first testis, x 3.5.

Plate XL\'I.

Fig 28, 29, 32. Hwniopls lateralin. Dorsal, ventral, and left lateral

views respectively of the anterior eight (-}-) somites. X 5-

Fig. 30, 31. Hcemopis lateraUti. Right lateral and dorsal views

respectively of the posterior end. x 5.

Fig. 33, 34. Hmmopin mannoraiis. Respectively left lateral and

ventral views of somites I to VIII and part of IX.

Plate XL\ II.

The three figures of this plate represent similar dorsal views of dissec-

tions which were selected because of the equality in size and apparent

ecjuality of sexual activity of the individuals. In each case almost

exactly the same extent of body is represented, as indicated by the

numbered ganglia, and the somites ccmtaining the testes are omitted.

All, X 7.5.

Fig. 35. Erpohdella puuctata. 'l"he left ovary and the right sperm
duct have been removed.

Fig. 36. Dina fervhJa.

Fig. 37. Dina microstoma.