BULLETIN
OF THE

Illinois Qtate | aboratory

OF

NATURAL HISTORY

Urbana, Illinois.

VOLUME V.

ARTICLE XI. NOTES ON SPECIES OE NORTH AMERICAN
OLIGOCH/E TA. IV. ON A NEW LUMBRICULID GENUS
FROM FLORIDA, WITH A DDITIONAL NOTES ON THE
NEPHRIDIAL AND CIRCULATORY SYSTEMS OF MESO-
PORODRILUS ASYMMETRICUS SMITH.

By frank smith, A. M.

Assistant Professor of Zoology, University of Illinois.

Illinois State Laboratory of Natural History.

UKBANA, ILLINOIS.

June 9, J900.

,»\0L0.

V ^/.,..



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.

{



Article XL

—

Xotcs on Species of North American Oligoelueta.

IV. On (I Neiv Linnbriculid Genus from Florida, ivith

Additional Notes on the Nej^hridial and Circulatory Sys-

tems of Mesojyorodrilns asyinmetricus Smith. By Frank
Smith.

Premnodrilus palustris n. g. et n. sp.

The worms here described were found by Mr. Adolph
Hempel in a decayed stump in a marsh in Polk county,

Florida, in March, 1897. The collection consists of eight

sexually mature individuals and a few others that are

imperfect or immature. The worms were killed in corrosive

sublimate and preserved in alcohol, and are in excellent

condition for study. All of the facts pertaining to this

species which are presented in this paper have necessarily

been obtained from an examination of this preserved material.

Sexually mature specimens, well extended, average about

50 mm. in length and 1 mm. in diameter at the tenth somite,

where the diameter is greatest. The body gradually decreases

in diameter toward the posterior end, where the somites are

relatively smaller and less distinct. The anterior end termi-

nates in a proboscis about .15 mm. in length, its diameter

being .07 mm. at the base and .035 mm. at the middle. In

these preserved specimens it is bent upwards. In five appar-

ently complete individuals the number of somites varies from

155 to 177, the average number being 167.

The clitellum extends from the anterior part of YIII to the

middle of XII, and is developed on the ventral surface. The
spermiducal pores are on the ventral side of IX (PI. XLL,
Fig. 1 ) ; the oviducal pores are in the groove between somites

X and XI and in line with the ventral setfe ; and the sperm-

athecal pores are on the ventral side of VIII, a short dis-

tance posterior to the ventral setfe of that somite. It will be

noted that the external openings of the reproductive organs

are further forward by one somite than is usual in the Lnm-
bricididce. The three sectioned specimens which form the

459



460 Illinois State Lahoratorij of Natural History.

basis of this description show uniformity throughout in the

position of the various reproductive organs.

There are four pairs of setfe in each of the setigerous

somites, the interval between the dorsal and ventral bundles

of one side of a somite being five sevenths as great as that

between the two ventral bundles and one half as great as that

between the two dorsal bundles of the same somite. The
setae are of the ordinary sigmoid form, without a cleft at the

outer extremity, and are somewhat variable in length, but

average about .2 mm. There are no genital sette.

The brain consists of two lateral masses, each with its

longest axis dorso-ventral, the two being connected by a stout

fibrous commissure. The surface layer of each mass, except

in the ventral region, consists of a thick layer of nerve cells.

The commissures extending to the ventral cord and the large,

nerve trunks leading to the prostomium are given off from

the ventral side of the lateral masses.

No marked peculiarities have been noticed in the alimentary

tract. There is a gradual transition from pharynx to intestine

without any well-marked intermediate oesophagus. The
anterior part of the pharynx is capacious, with a dorso-

ventral diameter considerably greater than the lateral one.

The ventral wall of the pharynx is quite thin, while a thick

glandular wall extends over the dorsal, and somewhat more
than half over the lateral, region. Toward the posterior

part of the pharynx the dorso-ventral diameter decreases, as

does also the extent of the thin ventral wall, and in the

anterior part of IV the walls are uniform in thickness and

circular in outline. The thickened part of the pharyngeal

wall is ciliated. Chloragogue cells first appear in the sixth

somite. There are no pharyngeal glands, but there are a

few deeply staining cells on some of the muscular strands in

a few anterior somites. On the anterior face of septum
VI/VII and on both faces of septum VII/VIII are borne

rather small masses of cells which do not stain very deeply.

They may correspond to the septal glands of some Oligochceta.

In that part of the body containing the reproductive organs

the lateral diameter of the intestine is greatly reduced (PI.



Praiinudriliis jidlusfris. 461

XLL, Fig. 3), so that the kmieii is a mere slit and the hiteral

walls are almost in contact.

The study of the circulatory system in this species, neces-

sarily conlined to sections of preserved material, has been

incomplete and somewhat dijfficult. The dorsal vessel con-

tains an extensive "Herzkorper" of nearly uniform diameter,

and similar structures are present in the lateral vessels of X
and of a few preceding somites. The ventral vessel forks

near the septum Ill/TV. In each of somites II-IX a single

pair of lateral vessels connects the dorsal vessel with the

ventral vessel or with its anterior branches. These vessels

have a somewhat tortuous course and are without chloragogue

cells. The lateral vessels of VIII follow the spermathecsi:^

into IX and sometimes farther, while those of IX extend

inside the sperm-sacs through a considerable number of the

succeeding somites. In somite X there are two pairs of

lateral vessels, the anterior pair connecting the dorsal vessel

with the ventral part of an extensive plexus of vessels in the

intestinal wall, and each vessel of the posterior pair extend-

ing posteriorly, through several somites, between the corre-

sponding sperm-sac and its inclosing membrane, and con-

necting the dorsal and ventral vessels. In somite XI and in

each succeeding one there are two similar pairs of lateral

vessels, which pass from the dorsal vessel outward and
downward near the body wall, and enter the intestinal

plexus on the ventral side of the intestine. A short blood-

vessel connects the ventral vessel with that part of the

intestinal plexus into which the lateral vessels of the anterior

pair open, and a similar vessel connects the ventral vessel

with the corresponding region of the plexus into which open

the vessels of the posterior pair. The lateral vessels of XI
and of succeeding somites have coecal diverticula, and those

of somites posterior to XI are invested with a layer of chlora-

gogue cells. In each of a few somites at the posterior end

there is but one pair of lateral vessels.

The nephridia are quite similar in structure to those of

other members of this group, the funnel being situated in

the posterior part of one somite, and the remainder of the



402 Illinois State Laboratori/ of Natural History.

nepliridium in the somite next following, with the nephridio-

pore a little anterior to the ventral set^e. On the duct, a

short distance posterior to the funnel, is a compact glandular

mass through which ramify minute ductules that seem to be

branches of the main duct. A considerable part of the coiled

region of the nephridium is in close relation to the dorsal

part of the ventral vessel.

The arrangement of the nephridia is an unusual one, or,, at

least, different from that ordinarily assumed to exist in the

Lumhricididce . In one of the sectio-ned specimens there are

no nephridia anterior to XIV, while in the other two there

are nephridia in VI-VIII but none in the following somites

anterior to XII, the first nephridiopores posterior to the

reproductive organs being in XII. In each of the two indi-

viduals having nephridia anterior to the reproductive organs

there is but one pair so situated, and the funnels of these

nephridia are in V, the nephridiopores in VI, and the main

masses of the organs extend along the dorsal side of the

ventral vessel into VII and VIII. Posterior to the clitellum

there is ordinarily but one nephridium in each somite,—an

examination of over a hundred somites affording but two

exceptions to this rule,—and the more common arrangement

is one in which there is on each side of the body, alternately,

a single nephridium in each of several successive somites.

In the three specimens studied there is but one pair of

testes in each, and these are borne on the posterior face of

septum VIII/IX ; but since there is a pair of spermiducal

funnels in VIII as well as in IX, it seems probable that there

has also been at some time a pair of testes in VIII.
'

The spermiducal apparatus is quite complex and somewhat

similar to that of Eclipidrilus and Mesoporodrilus (Eisen,

'95, pp. 87-89 ; Smith '96, pp. 404, 405). It will perhaps

be advantageous to mention briefly the principal structures

composing it before giving a detailed description. As already

stated, there are two pairs of spermiducal funnels, one on the

posterior septum of VIII and the other similarly situated in

IX (PI. XLL, Fig. 1). The two sperm-ducts of either side

extend backward to the posterior part of X or to the anterior



Premnodrilus jyalatitrls. 463

part of XI, where they enter the wall of the anterior end of

a long sperm-reservoir which extends backward through six

to eight somites. After passing through the muscular layer

of this wall the ducts pass between it and the inner epithelium

to the posterior end of the reservoir, where they open into

its cavity. The anterior part of the reservoir is continued

as a much narrowed and often considerably contorted duct,

which is continuous with the inner end of a large muscular

penial apparatus, the spermiducal pores being situated on

the posterior part of the ventral side of IX.

We can now go a little more into detail in describing the

spermiducal structures. As already stated, there are no

testes in YIII, although that somite contains a pair of sperm-

iducal funnels. The presence of an abundance of sperma-

tozoa in the sperm-reservoir and spermathecib and of well-

developed ova bears evidence that the animals had at least

reached a state of sexual activity, and yet the most careful

examination revealed not the slightest trace of testes in

VIII. A similar condition of affairs is described by Beddard

('92, p. 196) as existing in Sutroa alpestris, in which species

he found spermiducal funnels in IX and X but no trace of

testes in the former somite. The smaller and more variable

size of the funnels in VIII and the smaller diameter of their

ducts—which is only a third of that of the posterior ones

—

may reasonably be regarded as indicating a degenerate con-

dition, and that the complete disappearance of the testes has

preceded that of the funnels and ducts.

Each of the sperm-ducts leading from the anterior funnels

bends abruptly down, passing through the testis close to its

attachment to the septum. It then turns posteriorly and

passes into the extensive mass of muscular tissue surround-

ing the ventral part of the penial structure. After emerging

from this mass it extends upward for a short distance along-

side the muscular investment of the penis, passing along its

ental surface, and then extends across to the muscular duct

between the penial organ and the sperm-reservoir, Avhich it

follows to the latter organ, and, as before stated, passes

between its muscular layer and inner epithelial lining, along



464 Illinois State Laboratory of Natural History.

the ventral side of its cavity. Each of the sperm- ducts con-

nected with the posterior funnels extends at first directly

downward, and then, bencling posteriorly, takes a quite direct

course to the muscular duct, which it follows to the sperm-

reservoir. Passing then through the muscular coat of that

organ it extends posteriorly, having the same relation to the

muscle layer and lining epithelium as has the duct from the

anterior funnel, except that it lies on the dorsal instead of

the ventral side of the cavity and opens into the chamber at

a point nearly opposite the opening of the anterior duct.

Each sperm-reservoir lies in the sperm- sac of its own side,

and extends from the posterior part of X or the anterior part

of XI for a distance of six to eight somites. This organ has

powerful muscular walls, which are not constricted by the

septa, and which consist of a thin inner epithelial layer, a

thin layer of circular muscle fibers, and an outer and much
thicker layer of muscle fibers which are nearly longitudinal

but have a somewhat spiral course. Numerous' large cells,

apparently glandular in nature, lie outside the reservoir, and
are connected with its wall by elongated narrowed extensions

which presumably function as ducts, but have not been fol-

lowed beyond the superficial portion of the muscular wall.

The cells are altogether similar to those figured and described

by Eisen ('95, p. 88) as being numerous about the anterior

end of the "storage chsbmher" oi Eclip idrilus frigidus. In

Premnodrilus j^f^lustris, however, they are more abundant
near the posterior end of the chamber, and much less frequent

at the anterior end. Besides these large prostate glands,

following Eisen's nomenclature, there is a more or less inter-

rupted layer of smaller cells much like those called by Eisen

small prostate glands. The inner epithelium is everywhere

thin and the cell walls are indistinguishable.

Throughout the greater part of its length the sperm-

reservoir, exclusive of the layer of prostate cells, has a

diameter of about .25 mm., that of its lumen being about

.08 to .09 mm. The diameter of the reservoir diminishes

more gradually toward the anterior end than toward the

posterior, and the chamber tapers off into a muscular duct



Prenuiodriliis 2>iiliistri>t. 466

about 1 mm. in length, of which the diameter is ,015 to

.025 mm., while that of its lumen is .00') to .010 mm. The

walls of this duct include an inner epithelium, layers of

circular and longitudinal muscles, and an outer layer of

small, more or less isolated cells, like that already described

for the sperm-reservoir. This duct is usually contorted in

its course, and passes througli the muscular wall of the

inner end of the penial apparatus and opens into the inner

end of the greatly elongated penis. There is no " prostate"

nor "atrium" as in Edipldrilus fr'ufidiis, and the muscular

duct, which is perhaps comparable to the "bridge" of

E. friguliis, connects the sperm-reservoir directly with the

penis.

The proportions and relations of the penis in Premnodrilus

palustris can best be understood by reference to Fig. 1,

PI. XLI. The penial apparatus includes an elongated sac

lined with epithelium, continuous with the outer epithelial

layer of the penis proper, and, adjacent to this, a thick layer

of longitudinal muscle, outside of which is a delicate epithe-

lium. No layer of circular fibers is developed. In a speci-

men in which the penis is not much protruded the penial sac

extends upward and backward into the anterior part of XII,

the posterior septa of IX, X, and XI being forced back with

it. Strong muscular bands connect the free end of the sac

with the dorsal body wall of XII-XY, the strongest band

being in the posterior part of XIY. The long slender penis

is inclosed by the walls of the muscular sac, but is nowhere

connected with it except at its inner end. Its entire length

is 1.25 mm., of which .4 mm. is protruded from the body in

one of the specimens studied. Its diameter varies from .015

mm., near the tip, to .08 mm., near the point of attachment,

and at the middle is about .04 mm. Its unusual length is

doul)tless correlated with the correspondingly long sperm a-

thecal duct, to be described later.

The lumen of that portion of the sperm-duct which forms the

penis has a nearly straight course and is of small diameter,

being but ,005 mm. at a point midway of its length. The

penis is covered superficially by an epithelial layer continuous



466 Illinois State Lahoratorij of Natural History.

with that of the muscular sac inclosing it, while the lumen

of the sperm-duct which passes through it is surrounded by

an epithelial layer continuous at the inner end with that of the

muscular duct, and at the tip with the epithelium covering

the outer surface. Between these two epithelial layers is a

tissue composed of elongated cells, slightly inclined to the

long axis, which connect the inner and outer epithelial layers.

The cells are not as closely packed as are those of muscle

layers, and the tissue which they compose probably corre-

sponds to the "fibrous tissue" which is present in the atrium

of E. frigidus.

A pair of large elongated sperm-sacs extends backward

from the posterior septum of IX through twelve to eighteen

somites. A sperm-reservoir and its connecting ducts are

situated in the anterior part of each, and in one specimen the

spermathecfe also were included in the anterior part of the

sperm-sacs (PL XLL, Fig. 3). The posterior ]Dart of each

sperm- sac is constricted by the septa, and in the specimens

studied the cavities were filled with spermatozoa.

One pair of ovaries is present in the anterior part of X, and

a pair of oviducal funnels is borne on the posterior septum of

that somite, opening to the exterior in the groove between X
and XI. Large ova were present in but one specimen and

were contained in X. From the posterior part of that somite

a thin sheath of cells extends backward, enveloping the sperm-

sac, and including in the cavity between them the posterior

pair of lateral vessels of X. The posterior limits of this

sheath have been difficult to determine, and there is certainly

no appreciable space between it and the posterior end of the

sperm -sac, neither have any signs of ova been found within

it. It may be, however, that it represents an ovisac into which

ova might pass at a later stage of development.

There is one pair of spermathecae, opening on the posterior

part of the ventral surface of somite VIII. These organs are

unusually long and much differentiated in their structure.

In two specimens they push the septum VIII/IX backwards

into IX, forming contorted masses, while in the other speci-

men e^ch spermatheca extends posteriorly into the corre-



Prc))inodrili(.-; pdlustris. 467

spondiiig sperm-s;ie, and lies dorsad of the sperm-reservoir

and parallel with it (Fig. 3), one extending into XII and the

other as far as XYII. In two specimens, in which careful

measurements were made, the entire length of each sperma-

theca was a little over 3 mm., the greatest diameter being

.25 mm. The general form and proportions of these organs

can be readily seen in Fig. 2.

Each spermatheca includes three distinct regions, which

may be designated respectively as duct, storage region, and

glandular region. The duct is about 1 mm. in length, and

has comparatively thick walls, which consist chieiiy of longi-

tudinal muscle fibers. The muscular layer is thickest in the

middle of the duct and gradually thins out near the beginning

of the storage region. The diameter of both duct and lumen

is subject to considerable variation as shown by the following

measurements, which are very nearly the same for the two

spermatheca? most carefully studied. At a distance of

.25 mm. from the pore the diameter of the duct is .1 mm. and

that of the lumen .05 mm., and in this region the lining epithe-

lium is thrown into numerous high transverse folds, which

nearly fill the cavity. The diameter of the duct .4 mm. from

the pore is .1 mm., wdiile that of its lumen is reduced to

.02 mm. From this point to the beginning of the storage

region the diameter of the duct gradually decreases to

.045 mm., while the lumen at first increases to .045 mm.,

next decreases to .02 mm., and then enlarges into the cavity

of the storage region. The storage region is about .5 mm.
in length and has a diameter of .15 mm. for the first half,

then widens out to .22 mm., and is next constricted to

.14 mm. where the division between the second and the third

region occurs. Its walls are quite thin in the part nearest

the duct, but gradually become thicker and more glandular

and like those of the third region. This third, or glandular,

region is about 1.85 mm. in length, and its diameter is pretty

nearly uniform, varying only from .2 mm. to .25 mm., while

that of its lumen varies from .12 to .18 mm. The storage

region and the glandular region are not sharply differentiated,

but the former is filled with spermatozoa while the latter con-



468 Illinois State Lahoratory of Natural History.

tains but few or none, and the walls of the two regions are

decidedly different in structure except in the parts adjacent.

The sperm athecal wall consists of outer and inner epithelial

layers, in addition to which layers of muscle tissue are

present in the duct. The outer epithelium is everywhere

thin, and composed of flattened cells except near the middle

of the duct, where this layer is considerably thickened and

the cells are columnar in character. The inner epithelial

layer is of moderate thickness in the duct and in the greater

part of the storage region, and its cells stain quite deeply in

hfematoxylin. In the remainder of the storage region and in

the glandular part this layer becomes quite thick, and is

composed of columnar cells having their nuclei in the basal

portion and staining only slightly in Ehrlich's hfematoxylin.

A layer of circular muscle fibers, which lies next to the inner

epithelial layer and is comparatively thin, is present through-

out the whole length of the duct. Between this layer and the

outer epithelium there is a layer of longitudinal muscle fibers

which, is quite thick in the greater part of the duct, but thins

out, and finally disappears in the part nearest the storage

region.

From the foregoing description it is evident that Prcmno-

drilus palustris belongs to that branch of the Lumhriculidcs

which includes the peculiar genera Ecliindrilus and Meso-

Idorodrilus. For the purpose of studying the relationships of

these different forms, a more extended examination of the

nephridial and circulatory systems of Mcsojwrodrihis asym-

metriciis has been made, the results of which are next

recorded.

Nei^hridial and Circulatory Systems of MesojJorodrilus asym-

metricus Smith.

In the original description of this species the only reference

to the nephridia is to the effect that the first pair is in YII,

and that the nephridiopores are in front of the ventral setae

(Smith '96, p. 404). A re-examination of the material studied,

however, with more careful attention to the nephridia, shows

that the main masses of the pair belonging to YII extend



Mcsopodriliis (layminctrii-ns. 469

alongside the ventral vessel into IX ; that there are no other

nephriilia until we reach XII ; and that in this somite and in

each of the following ones there is but one nephridium, the

order of occurrence being that common in Pn'vuiodriliis

palustris, in which, as before stated, there is on each side of

the body, alternately, a single nephridium in each of several

successive somites. The asymmetry found to exist in these

two species suggests that possibly the views ordinarily held

as to the universality of the paired arrangement of the

nephridia in the Lumhricidida' may be due to the lack of a

careful examination of their distribution. On the other hand,

in Thinodrilus inconstant, in a species of Siitroa from Yellow-

stone Park, and in Eclipidr'dus frigidus,—the only other

species of Lnmbriculidce which have been accessible to the

author for study,—the nephridia are paired.

Our knowledge of the circulatory system is necessarily

incomplete, since the material for the study of this species is

limited to serial sections of parts of two specimens ; but it

has been possible to ascertain several facts concerning it.

As in many other aquatic Oligorhceta, branches of the

vascular system are freely distributed to the wall of the

intestine, taking either the form of extensive plexuses or of

sinuses of considerable extent. The ventral vessel is forked

near the septum Y/VI, and in each of somites II-V its

branches are connected with the dorsal vessel by one pair of

perigastric vessels. ^ In the anterior part of each of somites

VI-IX a pair of lateral vessels invested by gland cells con-

nects the ventral vessel with the dorsal part of the intestinal

plexus, while in the posterior part of each, a pair of slender

lateral vessels without investing gland cells and having a

somewhat tortuous course connects the dorsal and ventral

vessels. The relations of the lateral vessels in X are similar

to those existing in VI-IX, except that the posterior vessels

extend backward through several somites.

Before describing further the course of these vessels, it

> The terms perigastric, and gastric are applied as by Elsen, who calls lateral ves-

sels lying in the ccelomic cavity perigastric, and those closely associated with the

wall of the alimentary tract gastric.



470 Illinois State Laboratory of Natural History.

becomes necessary to correct the statement made in the

original description that there is but one sperm- sac (Smith

'96, p. 405), for while it is true concerning the specimen of

which transverse sections were made and in which the repro-

ductive organs were somewhat degenerate, in the other

specimen there are two sperm-sacs, one containing the

sperm-reservoir and the greater part of the spermiducal

apparatus, and the other, a considerably smaller one, belong-

ing to the other side of the worm, containing no trace of a

sperm-duct. Each of the posterior pair of lateral vessels of

X extends backward into the sperm-sac of its own side,

forming long loops in its course. In the specimen of which

transverse sections were made and in which there is but one

sperm-sac the posterior lateral vessel of X which is in the

side containing the sperm-sac extends posteriorly into that

organ for a distance of several somites, while the correspond-

ing vessel of the other side extends posteriorly for a similar

distance, and is closely invested by a layer of tissue which

doubtless represents a degenerate sperm-sac.

In the individual most carefully studied somites XI-XVII
have no perigastric vessels, but there seem to be two pairs of

gastric vessels in each (PI. XLI., Fig. 4). There is an ante-

rior pair of lateral vessels without coeca in each of somites

XVIII-XXIII, which leave the dorsal vessel as perigastric ves-

sels but unite with the intestinal plexus instead of the ventral

vessel. There is considerable variability in the positions at

which these vessels enter the intestinal wall. It may be any-

where from the ventral part of the intestine to a position two

thirds of the way from the ventral to the dorsal region (Fig. 5).

The posterior pair of lateral vessels in each of these somites

are gastric vessels. In each somite the ventral vessel is con-

nected with the ventral part of the intestinal plexus in the

two regions that are most closely related to the two pairs of

lateral vessels. A considerable number of somites posterior

to XXIII have not been sectioned, but of some of the poste-

rior ones sections have been made, the most anterior of which

has two pairs of perigastric vessels with coecal diverticula

:

an anterior pair, connecting the dorsal vessel with the ventral



NortJt Aineriran Lumhricitlid<e. 471

part of the intestiDal plexus ; and a posterior pair, connecting

the dorsal and ventral vessels. In several somites nearest to

the posterior end, both pairs of perigastric vessels have ca'ca

and connect the dorsal vessel with the ventral part of the

intestinal plexus.

Thus far, our knowledge of the Lamhriculidte of North
America has been limited to species collected in very restricted

and widely separated regions. Two species of Sutroa and
one of Eciipidrilus from California have been described by
Eisen ('81, '88, '92, and '95); one species each of Mcaoporo-

driliis and Thhiodrilxs from Illinois, by the writer ('95 and
'96); and this paper contains the description of a species

from Florida, for which still another genus name is proposed,

namely, Premnodrilns.^ Of these, Thuiodrilns is much more
nearly allied to Liimhriculns and certain other European forms

than to its North American associates that have thus far

become known, while Siitroa seems in certain particulars

intermediate between the European genus Rhynchelmis

(Vejdovsky, '76) and the peculiar group of North American
Lnmbriculidfe which includes EcUpidrilus, Mesoporodrllus,

and Premnodrilns. The species included in these three

genera are much more nearly related to each other, so far as

the structure of their reproductive organs is concerned, than

is any one of them to species of other genera of the family,

and yet the differences beeween them seem to the writer too

great to be considered'as merely specific. Thus, at present,

six species of North American Lumhricnlidte are known, and
they have been placed in five different genera.

Such a condition of things, in which we have in a com-

paratively small group of animals a number of genera nearly

or quite as great as the number of species, may be due to

one or more of several causes, and in this case it may be

owing to the fact that at present our knowledge of the Lum-
hricididte is insufficient to make it possible to determine which

• Leidy's descriptions of species presumably belonging to the Lumbriculida' are

inadequate and must be disregarded.



472 Illinois State Laboratory of Natural History.

characters should be regarded as generic and which as of

specific value merely. It is possible that an unusual varia-

bility in the reproductive organs exists in worms of this group,

and that in a similar length of time and under similar differ-

ences of conditions there might be a greater amount of

divergence in the character of these organs than there would

be in worms of other groups, as, for example, the earthworms,

and hence that differences which among the latter would be

generic ought perhaps to be considered as only specific when
found among the Lumhricnlitke . On the other hand, it may
be that species which now form the only members of the

genera to which they belong, will after a time, by the discov-

ery of other species, become types of genera which will each

contain two or more species more closely related to each

other than are the species now known, and thus the estab-

lishing of so many genera may be justified. In the case of

the three genera last referred to, when we consider that a

distance of a thousand miles intervenes between Florida and
Illinois and two thousand miles between Illinois and Califor-

nia, and that nothing whatever is known of the Lumbriculidce

of the intermediate regions, it seems reasonable to suppose

that subsequent collections from the intervening territory

may bring to light other species more nearly related to one

or more of them than they are to each other. Until future

collections and study shall disclose the facts, it seems best

to the writer not to include in one genus species which differ

so widely as do Eclipidrilns frigidus, Mesoporodrllns asym-

metricus, and Premnodrilus j^alustris.

A comparison of these three species will be facilitated by

the use of the following table, which includes characters that

are of more or less importance from the systematic stand-

point.



Xorth AnuTicdti Lumhriculidce. 473



474 Illinois State Laboratory of Natural History.

The principal features of the circulatory system of M. asym-

vietriciis and of that of P. palustris having alieady been

described at length in this paper, it has seemed unnecessary

to tabulate the characters of this system for all three genera,

and, instead, a summary from Eisen's description of E.

frigidus ('81, p. 3) is subjoined.

There is in E. frigidus but one pair of lateral vessels in

each of somites I-IX, and they are perigastric, connecting the

dorsal and ventral vessels, those of IX and X extending

posteriorly through several somites in connection with the

spermiducal organs. A considerable number of somites

following X contain only gastric vessels, of which there is

but one pair in each somite. Each of about thirty posterior

somites contains two pairs of perigastric vessels, which are

connected with the dorsal vessel and end blindly in the

coelomic cavity, all being short, and all more or less imper-

fectly forked or branched. There are no gastric vessels in

these somites.

An examination of the foregoing table shows that sperm-

reservoirs ("storage chambers") are present in all three

genera. These are specially modified regions of the sperm-

ducts, which are found in no other members of the family.

Other characters common to the three genera, but not so

distinctive, are the simple setfe, the eversible penes, and the

great extent of the sperm-sacs. These four characters taken

together may be regarded as distinguishing the subfamily

EdvpidriUnce from other LumhricuLdie. As the three included

genera contain but one species each, the definition of genera

and species is not attempted.

E. frigidus is distinguished from the other two members
of the subfamily by the absence of a prostomium and by the

presence of (1) several pairs of nephridia anterior to the

reproductive organs, (2) paired nephridia posterior to XII,

(3) but one pair of lateral vessels in each somite—excepting

thirty or more posterior ones in which are two pairs of

perigastrics ending blindly in the ccelomic cavity, (4) two

pairs of testes, (5) paired spermiducal pores onX, (6) paired

spermathecfe and spermathecal pores in IX, and (7) paired



XortJi American Lumbricullda'. 475

oviducal pores in the anterior part of XII. These differences

seem sufficient to warrant the recognition of the species as

generically distinct from the other two.

3/. asymmetricus and P. palnstris are more closely related

to each other than is either of them to E. frigidus. They,

alike, have (l)a prostomium, (2) but one pair of nephridia

anterior to the reproductive organs, (3) unpaired nephridia

posterior to XII, (4) one pair of testes, (5) two pairs of

lateral vessels in each of the somites posterior to X, and (6)

no perigastrics ending blindly in the cadom. They differ

from each other in several important respects, as follows

:

(I) in the position of the anterior nephridia, (2) in the

position of all the reproductive organs, (3) in the number of

sperm-ducts and spermiducal funnels, (4) in that the pros-

tate and atrium of M. asymmetricus seem to be replaced in

P. palustris by a greatly developed penial apparatus, (
">) in

the position of the spermiducal pores, (6) in the symmetry
or asymmetry of the sperm-sacs, (7) in the structure and

proportions of the spermathecae, (8) in the position of the

spermathecal pores, and (9), in a marked manner, in the

relations of the lateral vessels. As already intimated, only

future collections and study can make it possible to determine

whether these differences ought to be regarded as generic or

as merely specific ; but, all things considered, it seems the

wiser plan at present to regard the two species as generically

distinct.

The writer takes this opportunity to acknowledge his obli-

gatioifs to Mr. Hempel for his kindness in obtaining the

specimens of the new species described ; to Dr. Gustav Eisen

for several specimens of Eclipidrilus; and to Prof. S. A. Forbes

for the opportunity to study a species of Siitroa collected by

him in Yellowstone Park. The drawings for the figures were

made by Miss Lydia M. Hart, Artist of the Illinois State

Laboratory of Natural History.

University of Illinois, May 19, 1900.



476 Illi)iois State Laboratory of N((tural History.

LITERATUKE CITED.

Beddard, F. E.

'92. A Contribution to the Anatomy of Sutroa. Trans. Roy. Soc.

Edinb., Vol. XXXVII., Pt. 1, No. 13, pp. 195-202. 1 pi.

Eisen, G.

'81. Eclipidrilidse and their Anatomy. A New Family of the Limi-

colide Oligochttta. Nova Act. Reg. Soc. Upsala, III., pp. 1-10, 2 pis.

'88. On the Anatomy of Sutroa rostrata, a New Annelid of the

Family Lumbriculina. Mem. Calif. Acad. Sci., Vol. II., No. 1, pp.

1-8. 2 pis.

'92. Anatomical Notes on Sutroa alpestris, a New Lumbriculide

Oligochaite from Sierra Nevada, California. Zoe, Vol. II., pp.

321-334, PI. XIV.-XVI.

'95. Pacific Coast Oligochc'eta, I. Mem. Calif. Acad. Sci., Vol. II.,

No. 4, pp. 63-90, PI. XXX.-XLV.

Smith, E.

'95. Notes on Species of North American Oligochfeta. Bull. Ill State

Lab. Nat. Hist., Vol. IV., Art. VIII., pp. 285-297.
'

'96. Notes on Species of North American Oligocbaita. II. Bull. Ill-

State Lab Nat. Hist,, Vol. IV., Art. XIV., pp. 396-413, PI. XXXV.-
XXXVIII.

Vejdovsky, F.

'76. Anatomische Studien an Rhynchelmis Limosella Hoffm. (Euaxes

filirostris Grubei. Zeit. f. wiss. zool., Bd. XXVII., 3 Heft, pp. 332-

361, Taf. XXI -XXIV.



Plate XLI.



North American Lumbricididce. 477

EXPLANATION OF PLATES.

ABBREVIATIONS.

con. (/., duct connecting reservoir

and terminal portion of

penial apparatus.

Hit., clitellum.

dor.ves., dorsal vessel.

gl., glandular region of sperm-

atheca.

r/- ven., gastric vessel.

int., intestine.

»i. /., muscular fibers.

M(. I., muscular layer of sperm-

athecal duct.

«. c, nerve cord.

01'., ovary.

ov. d. /., oviducal funnel.

p., penis.

plex., intestinal plexus.

p. (I. res., perigastric vessel.

res., sperm-reservoir.

Sep. VIII., septum of VIII.

•s"p- '/•. sperm-duct.

sp. (I. /., spermiducal funnel.

sp.d.po., spermiducal pore.

sp. s., sperm-sac.

sp. th. fZ., spermatheoal duct.

sp.th.po.. spermathecal pore.

Kt., storage region of si)erm-

atheca.

/., testis.

I', ves., ventral vessel.

Plate XLL

Pre 771 7iodrilus palustris

.

Fig. 1. A diagrammatic representation of a part of the rejiroductive

organs. X 35.

Fig. 2. A diagrammatic longitudinal section of a spermatheca, recon-

structed from a series of sections, x 50.

Fig. 3. A transverse section of XI, from a specimen in which, the pos-

terior parts of the spermatheca* were included within the

sperm-sacs. X 45.



478 Illinois State Laboratory of Natural History.

MesojJorodrilns asymmetricus.
,

Fio. 4. Prom a longitudinal section through XIII, showing a part of

the circulatory system. X 85.

Fig. 5. A part of the circulatory system in XXI, composed from several

transverse sections, x 75.