Bulletin STATE OF ILLINOIS HKXRY HORNER, Governor DEPARTMENT UK REGISTRATION AND EDUCATION DIVISION OK IHE XATl RAL HISTORY SL'RVKY THEODORE H. PRISON. Chkr Volume 21 BULLETIN Article 3 Studies of Nearctic Aquatic Insects I. NEARCTIC ALDER FLIES OF THE GENUS Sialis (MEGALOPTERA, SIALIDAE) H. H. ROSS II. DESCRIPTIONS OF PLECOPTERA I', II. PRISON PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS September 19,?7 STATE OF ILLINOIS Henry Horner, Governor DEPARTMENT OF REGISTRATION AND EDUCATION John J. Hallihan, Director BOARD OF NATURAL RESOURCES AND CONSERVATION John J. Hallihan, Chairman William Trelease, D.Sc, LL.D., Biology William A. Noyes, Ph.D., LL.D., Henry C. Cowle.s, Ph.D., D.Sc, Forestry Chem.D., D.Sc, Chemistry John W. Alvord, C.E., Engineering Edson C. Bastin, Ph.D., Geology Arthur Cutts Willard, D.Eng., LL.D., President of the University of Illinois NATURAL HISTORY SURVEY DIVISION URBANA, ILLINOIS Scientific and Technical Staff Theodore H. Prison, Ph.D., Chief SECTION OF ECONOMIC ENTOMOLOGY W. P. Flint, B.S., Chief Entomologist C. C. CoMPTON, M.S., Associate Ento- mologist M. D. Farrar, Ph.D., Research Ento- mologist J. H. Bigger, B. S., Associate Ento- mologist S. C. Chandler, B.S., Southern Field Entomologist L. H. Shropshire, M.S., Northern Field Entomologist W. E. McCauley, M.S., Assistant Entomologist C. W. Kearns, Ph.D., Research Fellow in Entomology J. F. Alsterlund, M.S., Research Fellow in Entomology DwiGHT Powell, M.S., Research Fellow in Entomology L. R. Tehon, Ph.D., Botanist J. C. Carter, Ph.D., Assistant Botanist G. H. BoEWE, M.S., Field Botanist SECTION OF FORESTHY James E. Davis, M.F., Exteniion For- ester SECTION OF AQUATIC BIOLOGY David H. Thompson, Ph.D., Zoologist F. D. Hunt, Field Naturalist D. F. Hansen, A.M., Assistant Zoologist D. J. O'Donnell, M.S., Assistant Zo- ologist SECTION OF INSECT SURVEY H. H. Ross, Ph.D., Systematic Ento- mologist Carl O. Mohr, Ph.D., Associate Ento- mologist, Artist B. D. Burks, Ph.D., Assistant Ento- mologist R. E. Yeatter, Ph.D., Game Specialist W. H. Leigh, M.A., Assistant Zoologist SECTION OF PUBLICATIONS Carroll Chouinard, M.A., Editor TItis paper i tlrihulion/rnni the Sectio (31401—1200—6-37) of Insect Survey I CONTENTS i. nearctic alder flies of the genus sialis (megaloptera, sialidae) Biology and Ecology 57 Habitat preference.—Distribution.— Physiological segregation of species. — Preservation and preparation of material.—Illustrations.—Value of char- acters.—Terminology of genitalia. Taxonomy 59 Acknowledgments.— Present holders of material: s>niliols. Description of Species 60 Sill/is—generic characteristics—key to nearctic species.— .S'. joppa.— .">'. nrvalis.—S. iola.— S. californica.— .?. occidens.— S. cornula.—S. hamata.— S. americana.— S. glabella.— S. velata.— .V. ilasca.— S. infiimala.— .S'. con- cava.— S. hasta. .?. mnhri. S. rotunda. .V. nevadensis. tV. varans.—S. aeqnalis. Bibliography 77 II. DESCRIPTIONS OF PLECOPTERA, WITH SPECIAL REFERENCE TO THE ILLINOIS SPECIES Rksults FROM New Materiai 78 .\i)i)irioNs TO THE Illinois Plecoptera 79 .icroneuria evoluta.—.]. perplexa.— Togoperla kanserisis—key to species of Togoperla.—Hydroperla varians— key to nymphs of llydrupcrhi. Xdoitions to Nearctic Plecoptera Not Known in Illinois , . 8,? iVeniottra oregonensis.—N. tubercuUUa.—Leiictra jorcipata. —F^ucapnopsis brfcicatida.—Capnia distincta.— C. excavata.—C. projectu.—C. promota.— Diclyuplerygella knowlloni.—Hydroperla parallela.— Chloroperla orpha.— Isoperla pinta.—/. truncata.—Alloperla exquhita,—.1. occidens. .Synonymy 97 .Icroneuria tycorias.— Togoperla inimarginala.— T. media. Bibliography 97 Index. ILLINOIS NATURAL HISTORY SURVEY BULLETIN VOL. 21, ART 3 SEPTEMBER 1937 Studies of Nearctic Aquatic Insects I. Nearctic Alder Flies of the Genus Sialis ( Megaloptera, Sialidae i HKRBERT H. ROSS BIOLOGY AND ECOLOGY IN American literature the genus Si/ilis has been in confusion for some time because of the fact that all authors, except Kanks, have recognized only three nearctic species, anier'uaiia, iievadensis and infujiiata. Americana and nevadeiisis differ from infumata in color and sculpturing and have long been recognized correctly. Everything else has been grouped under injiiiiKitd. The only effort to enlighten the problem was made by Banks, who described four species chiefly on the basis of genital characters. In spite of this prophetic indi- cation, no other extensive work has been done. Critical study of the genitalia has re- vealed no less than 10 eastern and six western species grouped under the name infuinata. As a result the observations and records in literature of "Sialis itifuinata" can have no specific validity unless the actual specimens involved are re-identified. The biology and liabits of the genus have been treated in detail by Davis ( 1903), so that only a brief resume taken chiefly from his study need be given here. The Sialis adults, fig. 1 (p. 58), with few e.xceptions are fairly large, black, broad insects, only moderately rapid in their movements. They are diurnal, most active during the middle of the day. The eggs, fig. 2, are cylindrical, rounded at the top and have an apical curled tassel. They are laid in rows forming large masses, situated on branches, bridges, and other objects hang- ing over water. Upon hatching, the larvae, hg. .?, presumably fall into the water. where development takes place. The larvae are predaceous, hunting under stones, etc., for their prey. Respiration occurs through the tracheal filaments on the sides of the abdomen. When full grown the larvae crawl out of the water and dig into the bank to form an earthen cell several feet from the water's edge. Here pupation occurs, the adult emerging from this pupal cell. The life of the adult is probably short, since it has soft mouthparts which do not appear fitted for extensive feeding. Habitat Preference Judging from present data the species inhabit all variety of fresh-water situations in which aeration is good. The habitat range, therefore, is from small streams to large rivers and lakes, and for the same species it may be equally variable. Thus in Illinois S. velata has been taken onh along rivers whereas iiiohri has been taken abundantly along rivers and around the northern lakes. In Michigan, however, Dr. T. H. Prison has taken both these species in large numbers on Houghton lake, associ ated unmistakably with the lake fauna. Se.asonal Succession.—The adults occur with the early spring fauna in Illinois, and at a proportionately later date farther north. Data on hand certain- ly indicate a seasonal succession of species within the genus. Collecting dates for the three commoner eastern species indicate that velata appears earliest in the season, iiiohri soon after and itasra last. Average dates for the collection of males of these three in Illinois are, respectiveh', April 27, 58 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 3 May 21 and June 13. This tells neither the duration of the emergence period nor the overlapping between species, but it gives some approximation of the difference in time between peaks of abundance. Dr. Prison made a large collection of velata and /iioliri at Houghton lake, Mich., June 15 to 18, 1935, which gives a good illustra- tion of the overlapping of these species where they occur in the same habitat. The earlier species velata was represented by 7b specimens, of which 67 per cent were fe- males, all extremely gravid ; nioliri was represented by 353 specimens of which only 47 per cent were females, half of which appeared relatively fresh. From this it would seem that the population wave of one species breaks over that of the pre- ceding species soon after the latter begins to wane. Distribution With the small amount of material col- lected at present, plotted records of indi- vidual species give only scanty maps. Even so a few interesting points are brought out. Some species, such as velata and mohri, are widespread, occurring from the Atlantic to the eastern base of the Rocky moun- tains. On the other hand, iola is restricted to the Appalachian region. Several species are distinctly western, occurring in the Rocky mountain region or westward, as for example, californica, haiiiata and rotunda. Physiological Segregation of Species There are several pairs of species in Sinlh which are very closely related, such as the combinations velata-itasca, aeqiialis- vagans, iola-joppa and califoniica-occideits. Analysis of their known distribution rec- ords brings out the following points: (1) Both members of such a pair of species have never been collected together at the same time and place. In the case of lola and jnppa the geographic range and seasonal timing of both species are appar- ently quite similar, but in no case have specimens of both been submitted bearing exactly the same collection labels. This would indicate that each species has a dif- ferent habitat preference within the same range. (2) In the case of velata and itasca we have two forms with approximately the same range. All data indicate, however, that tiie two species have radically different seasonal adjustments, velata appearing early and itasca late, their average col- lection dates for the same locality being four to six weeks apart. (3) The pair califoniica and occidein present an interesting type of difference in range. Californica occurs through the Rockies from north of 50° to at least north- ern California, and down the coastal range to Kern county, Calif. On the other hand, occideus has so far been collected onl\- Fig. l.~Adult of Sialis around Reno, Nev., and the upper Sierra i Nevada in California. A similar marked difference in range is shown by the eastern pair, aequalis and I vayaiis. The former is distinctly a southern i and eastern species of restricted range, hav- ing been collected in Virginia, Maryland, , New Jersey and southern Pennsylvania. The range of vagans begins where that of aequalis ends, and continues north to Que- bec and west to Illinois and Michigan. The northern species has a much more ex- • tensive range than the southern one. This information shows that the morphological differences which are tlie tangible characters separating the species • recognized in this paper coincide with i physiological differences expressed by eco- • logical orientation. September F'i? ROSS: NEARCTIC ALDER FLIES 59 Preservation and Preparation of Material The most satisfactory method of pre- serving specimens seems to be in fluid. We have used 80 per cent ethyl alcohol witii good results. Genitalia and other diag- nostic parts of specimens so preserved usually may be seen without injuring the specimen or performing other preparation. If a specimen is pinned, its abdomen must usually be removed and cleared before it is possible to give a complete diagnosis. The follow technic has been used with fine results: soak the abdomen for three to six hours in cold 10 per cent caustic potash (KOH) solution, change to distilled water for an hour or more, then with for- ceps and needle gently press out the dis- solved viscera. This leaves a fairly trans- parent shell which may be preserved and studied in 80 per cent alcohol or glycerin. Illustrations The illustrations of genitalia used in this paper are made from specimens treated in caustic potash solution. They are drawn with the parts considerably expanded, since it is only in such a position that some details can be seen clearly. Value of Characters Genitalia have provided the best char- acters for separation of species, although other characters may be of value. Differ- ences in wing venation are subject to considerable individual variation and ma\ be expressed at best as averages and not as absolute characters. For example. (/ilifornica usually has three or four branches of R,, but may have only two, whereas velata and some others usualh have only two branches of R2 but ma\' have three or four. The cross-veins of the costal area of the front wing vary in the same fashion: americana has four to six, nioliri has four to 10, averaging seven, and the others have 10 to 15, averaging 12 or more. Differences in punctuation and gloss of the head are quite constant, but offer no differences between many species. It is difficult to express some of these char- acters, since the differences are relative and can be recognized only after acquaintance with the various types. Terminology of Genitalia Use of genitalia necessitates a terminol- ogy for its components, and since no one has homologiz.ed them definitely witii those of other insects an original set of terms is proposed for them. No attempt is made here to homologize these parts; instead the names are purely descriptive and are used as a convenience. The names applied to the genital parts are as follows: (1) Lateral plates: a pair of plates on the venter beyond the eighth sternite, tii;. 4, 1, p. 000. (2) Terminal plate: a single plate on the caudal enil ot the abdomen, which a.ssumes many shapes, (ig. 4, t. (3) Genital plate: a pair of sclerites forming a more or less solid plate on the venter between the above two parts, fig. 4, g. From this arise various appendages called genital hooks, figs. 12, 28. Fig. 2.—Eggs ot Sinlis mohri. TAXONOMY From the standpoint of ph\ logenetic position Sialis is an interesting genus. Many generalized features of its structure and biology place it as one of the most archaic genera of holometabolous insects. The group comprising Sialis, Cnrydalis Chauliudes and allied genera has been con- sidered by some authors as a member of the order Neuroptera and by others as a separate order Megaloptera. Due to its apparent axial position with reference to the phylogenj- of the Neuroptera, Mecop- tera and Hynienoptera, it seems clearer to designate the group as a distinct order. Most recent authors consider that the fainily of Sialida: is composed of two well- marked subfamilies: the Sialinne, including Sialis, and the Corydalinre, including Corydalis, Cliauliodes and their allies. The separating characters between tiir two groups seem of sufficient magnitude to warrant recognition of each as a distinct 60 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'M ROSS: NEARCTIC ALDER FLIES 63 KEY TO NEARCTIC SPECIES OF SIALIS Apex of abtiomen with broad, rounded ovipositor, fig. 51 (temales) 20 Apex of abdomen without an ovipositor but with a more or less complicated assemblage ot parts, figs. 4-15 (males) 2 Kront between eyes with a prominent hornlike process, fig. 43 rotunda Front between eyes without a hornlike process 3 Ninth sternite produced into a flap covering most of the genitalia, figs. 11-15 4 Ninth sternite not produced into a flap, figs. 4, 34 6 Apex of lateral plates with a strong tooth, fig. 15 nevadensis .Apex of lateral plates without a tooth 5 Terminal plate wide with apex divided into two large processes, fig. 25b . aequalis Terminal plate narrowed at apex and not markedly incised, fig. 23b, vagans Terminal plate produced at apex into a pair of long arms, figs. 31b, 32b. , . 7 Terminal plate sometimes with an api- cal incision, fig. 28b, or a pair of short "horns," fig. 19b, but not with a pair ot long arms 8 Apical arms of terminal plate separ- ated at their base by a distance almost equal to their length, fig. 31b hasta .Apical arms of terminal plate close to- gether at base and converging at tip, fig. 32b mohri Legs with temora rufous and tibiae the same color or blackish 9 Legs black, or with tibiae slightly lighter than temora 10 Head smooth and polished glabella Head punctured and dull americana Genital hooks long and whiplike, figs. 28-33, extending forward between the lateral plates, figs. 34-39 11 Genital hooks short, never longer than the plate from which they arise, figs. 16-21; lateral plates always closely appressed on meson, figs. 4-9 14 .Apex of lateral plates produced into large knobs, fig. 36 infumata Apex of lateral plates not knoblike .... 12 Terminal plate long, its apex slightly enlarged but not cleft, fig. 33b; genital hooks simple, without a basal lobe, fig. 33a concava Terminal plate short, its apex markedly cleft, fig. 29b; genital hooks with a basal lobe, fig. 29a 13 Basal lobe of genital hooks smaller, as in fig. 29a; terminal plate as long as genital hooks are high, fig. 29b velata Basal lobe of genital hooks markedly robust compared with distal lobe, fig. 28a; terminal plate shorter than genital hooks are high, fig. 28b. itasca .Apex ot terminal plate produceil into two short, stout, curved "horns," fig. 19 cornuta .Apex of terminal plate not with horn- like processes 15 .Apex of terminal plate produced into a thin, flat "neck," at the end of which the genital hook articulates, fig. 20; this hook, fig. 20a, strongly recurved to form the swan's neck type of hook hamata .Apex of terminal plate without a neck- like process, fig. 21; genital hooks not recurved 16 Basal portion of genital plates, figs. 21, 49, projecting above apex of terminal plate; ninth sternite with lateral setae long and whiskerlike, fig.8.... ....17 Basal portion ot genital plates neither enlarged nor projecting over terminal plate, figs. 16 to 18a, ninth sternite with fairly short lateral setae, figs. 4, 9 18 Genital plate as in figs. 8 and 21a, the base narrow and produced into two bulbous elevations califomica Genital plate as in fig. 49, the base wider, and not produced into two bulbous knobs occidens Terminal plate with the apex narrow, tapered to a blunt point and not in- cised on meson, fig. 18b iola Terminal plate with apex wider, and either markedly incised or almost truncate, figs. 16, 17b 19 Terminal plate almost as wide as long, more or less pentagonal, fig. 17b; genital plates more than a third as long as terminal plate, fig. 17a. . joppa Terminal plate 1}4 times as long as wide, more or less quadrangular, fig. 16b; genital plates less than a fourth as long as terminal plate, fig. 16a. . . . arvalis Ninth sternite large, triangular and distinctly sclerotized, fig. 56 . . .mohri Ninth sternite apparently membranous and difficult to distinguish in un- cleared specimens 21 Eighth sternite large and with a long narrow cleft on the apical margin, fig. 63 nevadensis Fighth sternite never with such a clett . 22 Legs with femora rutous and tibiae the same color or darker than temora. . .23 Legs either entirely black or with the tibiae lighter than the temora 24 Head smooth and polished glabella Head punctured and dull americana Both clypeus and front just above it with a small but fairly conspicuous tuft of black hairs on the meson. Median depression ot eighth sternite very large and deep, fig. 55 . . . .rotunda Clypeus and front without any trace 64 ILLINOIS NATURAL HISTORY SURVEY BULLETIN V^ol. 21, Alt. J Genitalia of Sialis Males Fig. 16.—S. arvalis. Fig. 20.—S. hamata. Fig. 24.^S. rotunda. Fig. 17.—S. joppa. Fig. 21.—S. califomica. Fig. 25.—S. aequalis. Fig. 18.—S. iola. Fig. 22.—S. americana. Fig. 26.—S. lutaria. Fig. 19.—S. comuta. Fig. 23.—S. vagans. Fig. 27.—S. nevadensis. Abbreviations.—a, lateral view of genital and terminal plates; b, caudal view of terminal plates; g, genital plate; 1, lateral plate; t, terminal plate. «l September 1937 ROSS: NEARCTIC ALDER FLIES 65 37 38 Genitalia of Sialis Mai.f.> Fip. 28.— S. itasca. Fig. 32.—S. mohri. Fig. 29.—S. velata. Fig. 33.—S. concava. Fig. 30.—S. infumata. Fig. 34.—S. itasca. Fig. 31.—S. hasta. Fig. 35.—S. velata. Abbrkvia I'lONS.— a, Literal view ot genital and terminal plates; b, caiulal view of terminal plate; g, genital plate; 1, lateral plate; t, terminal plate; 9, ninth sternite. Fig. 36.—S. infumata. Fig. 37.—S. concava. Fig. 38.—S. hasta. Fig. 39.—S. mohri. 66 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'ol. 21, Art. 3 SiRlICTlIRES OF SlAI.IS MaI.KS AND FeMAI.F.S Fig. 40.—Costal area of front wint; of S. Fig. 46.—Lateral view of bursa copulatrix ot :ilcibella. S. infumala. Fig. 41.—Costal area of frcint wing of .S". Fig. 47.— Dorsal view of head of male i\ niohri. i-otunda. Fig. 42.— Costal area of front wing of S. Fig. 48.—Dorsal view of head of .9. «^Mrt'<'H- infnmala. sis. Fig. 43.—Lateral view of head of male S. Fig. 49.—Genitalia of male 5. occidens. rolunda. Fig. 50.—Lateral view of bursa copulatrix of Fig. 44.—Lateral view of head of female S. S.joppa. rolunda. Fig. 51.—Lateral view of abdomen of female Fig. 45.—Genitalia of male S. glabella. S. infumala. Abbrf.viations.—a, lateral view of genital and terminal plates; b, ventral view o( genital ]>larc and hooks; h, humeral cross-veins; o, ovipositor; 7, 8, 9, abdominal sternites. KEY TO NEARCTIC SPECIES OF SIALIS—Concluded of a tuft of hairs. Median depression of eighth sternite not as large 25 Eighth sternite narrow and divided into two separate lobes by a median de- sion, fig. 57 aequalis, vagans Eighth sternite either wider, fig. 60, or not divided so completely into two separate parts, fig. 54 26 Eighth sternite as in fig. 60, rectangular and with the distal portions set out as distinct swellings infumata Eighth sternite not as in fig. 60, either with apex rounded out, fig. 53, or not set off with such conspicuous lobes 27 P.ighth sternite flat, not tilted so that the apical margin is raised, fig. 54. Bursa copulatrix with a terminal fingerlike process velata, itasca Eighth sternite tilted so that the apical margin is markedly raised and basal margin depressed, figs. 53, 59. Bursa copulatrix with terminus triangular, fig. 53 28 Species occurring only east of the Great Plains region iola, joppa Species occurring only west of the Great Plains region 29 Median depression situated near the tip of a long, slender mesal process on the apical margin of the eighth sternite, fig. 52 hamata Median depression not situated on such a long slender process 30 Apex of eighth sternite not evenly rounded, fig. 59. Lateral area of eighth sternite with abundant and dark setae californica, occidens Apex of eighth sternite evenly rounded, much as in fig. 53. Lateral area of eighth sternite with considerably less abundant and light-colored setae. . . . cornuta September 1937 ROSS: NEARCTIC ALDER FLIES 67 Apical Sternites of Sialis Females Fig. 52.— .v. hiimiild. Fig. 53. — S'. jo/tpa, .showing Inirsa copul.Ttrix in situ. Fig. 54.—S. velata showing bursa copu- NWbatnx in situ. Jj^ Fig. 55. — S. rntnnda. ^^" Fig. 56.— ,V. mohri. Fig. 57.— .v. uequalis. Abbreviation.s.— c, bursa copulatrix; 7, 8, 9, alulominal sternites Fig. 58.— .v. amfriccDia, Fie. 59.— .V. ailifornica. Fig. 60. — S. injumata. Fig. 61.—Lateral view of bur of .S\ yievadensis. Fig. 62.— Bursa copulatrix of S. neiiadens as seen through venter of abdomen. Fig. 63. — S. yievadensis. copulatrix Sialis joppa — new .species MALE.—Length 12 mm. Head, body and appendages black with the following excep- tions : raised lines and dots on head and nar- row ring around ej'e, yellowish ; legs shad- ing to brown ; wings dark brown, slightly lighter towards ape.x. General Structure.—Front and ad- joining portion of vertex slightly roughen- ed but highly polished, concave. Remainder of head dull and shagreened except raised areas on front and vertex. Front wing with eight to 12 supernumerary cross-veins in costal area; radius 3 with two or three branches. Abdomen and genitalia as in figs. 4 and 17. Ninth sternite narrow and bandlike, clothed with abundant short setae, and sometimes with depressed area on the meson of the basal margin. Lateral plates more or less ovoid, typically closely appressed on meson. Genital plate small, as wide as its mesal length, with a pair of short, closely appressed genital hooks, fig. 17b. Termi- nal plate ovoid, fig. 17a, tending to be pentagonal, ventral margin or apex form- ing two low rounded lobes separated by a slight incision on the meson. FEMALE.—Length 14 mm. Color and general structure as in male, except for the 68 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 3 head, which may be swollen behind the ejes. Abdomen and genitalia as in fig. 53. Seventh sternite heavily sclerotized, ap- pearing longer than wide due to convexity ; sometimes with a small swelling on meson near apex. Eighth sternite tilted, the base depressed and apex raised; the mesal portion slightly depressed longitudinally ; the setae only moderately long. The apical margin of the segment bears a small round depression on the meson ; if the segment is stretched out there can be seen a small pointed process running forward from under this depression. Ninth sternite mem- branous but fairly rigid, forming a wide V. Tip of bursa copulatrix entirely membran- ous, fig. 50, triangular in dorsal view, fig. 53. Holotype, male.—Newfound Gap, Great Smoky Mountain National Park, N.C.: May 28, 19.U, T. H. Prison, inhs. Allotype, female.—Same data as for holo- type. Paratypes.—Same data as for holotype and allotype, !&, 19. Illinois.— Eichorn, Buck creek: Apr. 22, 19.32, Ross & Mohr, Id', inhs. Maine.—Naples: Farley, Icf, inhs. New Hampshire.—White mountains, Al- pine: Icf, inhs. Gorham: Icf, mcz. New York.—Crosby: May 20, 1920, Id', cu. Ithaca: May 23, 1915, 1 d', cu. McLean: June 2, 192,3, Id', inhs. Stanley: May 17-20, C. R. Crosby, IcT, inks; 19, cu. VVilliams: May .31, 1913, 2&, 29, cu; Id', 19, inhs. North Carolina.—North fork Swannanoa river. May, Icf, mcz. Ohio.—Sugar Grove: April 17, 1902, Id', osu. Pennsylvania.—Castle Rock: May 21, 1908, Id", ANs. Jeanette: H. G. Klages, Id', CM. Two miles north of Narberth, Montt^omerv county: May 16, 1925, E. T. Cresson, }r., 1 d'', ANS. Philadelphia: May 11, Icf, inhs. This is a decidedly eastern species, its distribution resembling that of /o.V;. The Ohio and Illinois records, however, are more western than any records of iolri Total size and color of wings vary con- siderably in both sexes. This species is closest to arvalis and tola but may be sepa- rated from them in the male by the shape of the terminal plate. The females of this entire group are difficult to separate. Sialis arvalis—new species MALE.—Length 11 mm. Color and gen- eral structure similar to joppa. Differs only in details of abdomen and genitalia figs. 6, 16. Ninth sternite bandlike, clothed with scattered short setae. Lateral plates somewhat ovoid, mesal side angular and appressed on meson for a short distance. Genital plate very small, quadrate and with a pair of short genital hooks, fig. 16a. Terminal plate, fig. I6b, rectangular in general outline, the apex divided into two lobes which are considerably swollen. FEMALE..—Unknown. Holotype, male.—Mokel Hill, Calif., April, F. E. Blaisdell, cas. Paratypes. California.—Mokel Hill: F. E. Blaisdell, Icf", cas; Icf, inhs. Yorkville, Men- docino County: April 30, 1934, E. P. Van Duzee, 1 cf, cas. Sialis iola—new species MALE.—Length, color and general struc- ture similar to joppa. Differs only in details of genitalia, figs. 9, 18. Ninth sternite bandlike and with onh' moderately long setae. Lateral plates more or less ovoid and appressed on meson. Genital plate small, narrower than its mesal length, with a pair of short, closely appressed genital hooks, fig. 9. Terminal plate triangular in general outline, the apex round and very narrow, without an incision on the meson. female. —Apparently identical with that of joppa. Holotype, male.— Pittsburgh, Pa. inhs. Allotype, female.—Same data as for holo- tvpe. Washington, D. C—April 1928, id', 19, nm; Id' , 19, INHS. New Jersey.—Riverton: May 4, 1903, 2d', INHS. Paterson: June 10, 1 cf, am. New Hampshire.—Durham: lcf,cu. New York.—Axton, Adirondack mountains: June 12-22, 1901, 5d', 19, cu; 2d', 19, inks. Black brook, Clinton county: June 11, 1916, Icf, 19, cu. McLean: May 31, 1913, Icf, 19, inhs; Icf, 19, cu. McLean bogs, Tompkins county: May 29, 1915, Icf, cu. Ringwood, Ithaca: June 26, 1920, 1 d', 19, cu. Pennsylvania.— Inglenook: May 31, 1914, Id', MCZ. Pittsburgh: May 22, 1899, 1 cf, cm. Quebec— Fairy lake: June 1, 1927, 19, cnm. Knowlton: June 5-14 and fuly 12, 5cf , 59, cnm; 5d', 59, inks. Lachine: iune4, 1930, I.. J. Milne, Icf, CNM. Sialis californica Banks Sialis Juliginosa Davis (1903, p. 449) in part \nec Pictet|. Sialis injumata Davis (1903, p. 448) in part \nec Newman). Sialis californica Banks (1920, p. 326). ., MALE. —Length 11-14 mm. Color and J general structure as in joppa e.xcept that many specimens are larger and have the wings solid iridescent black. This darker coloration intergrades to a liglit brown in a long series. SeptfiiiluT I'l.U ROSS: NEARCTIC ALDER FLIES 69 Abdomen and t;enitalia, figs. 8, 21. .Ninth sternite bandlike, the mesal portion clothed with only moderately long setae, but the lateral portions bearing many long setae which project considerably beyond the lateral margins of the segment to give the appearance of a bushy set of cat's whiskers, fig. 8. Lateral plates ovoid, appressed for a distance on the meson. Genital plate narrow, evenly tapered to apex where it is produced into a pair of short hooks; the base of the plate, fig. 21a, bulbous and raised above the apex of the terminal plate. Terminal plate, fig. 21b, triangular in out- line, the extreme apex rounded but not divided into two lobes. FEMALE.—Length 12-16 mm. Color and general structure as in male. Abdomen and genitalia as in joppa with the following differences: eighth sternite, fig. 59, with the apical margin raised, in- cised on meson, the mesal depression fairly large and bounded apically by a narrow bridge ; basally from this extends a fan- shaped, concave area with few or no setae; on either side of this the segment is raised and these raised areas are clothed with setae which are longer than those on other females in the callfnrnica group. Bursa copulatrix with the tip more or less sclero- tized, triangular from the ventral aspect, somewhat beaked from the lateral aspect. Lectotype, male, by present designation. — San Emiedio canon, Kern county, Calif.; F. Grinnell jr., June 3, 1904, Type * 10844, mcz. .Alberta.—Jasper to Buffalo Prairie: June 30, 1915, IcT.iNHS. British Columbia.— .Alta lake, Mons: June 11, 1926, J. McDunnough, Icf, 19, cnm. Goldstream: June i, 1923, K. F. Auden, 19, CNM. Ucluelet: July 20, 1909, C. H. Young, 1 cT, CNM. California.—Alameda county: Id', inhs. Berkeley: April 14, 1928, Id', cas; April 27, 1921, Id', INHS. Big Basin Park, Santa Cruz county: May 12, 1918, Id", cas. Carrville, Trinity county, altitude 2400-2500 feet; May 19, 19,?5, Id', 29, cas; Id', 19, inks. Eureka; June 6, Icf, nm. Phoenix lake, Marin county; April 4, 1927, 1 cT, 19, cas. San Emigdio canon, Kern county: Icf, mcz, paratype; \&, inhs, paratype. San Jeronimo: Icf, mcz, paratype; Icf INKS, paratype. Yorkville, Mendocino county: May 1, 1924, cas. Oregon. -^Albany; April 25, 1934, T- Schuh, 19, INHS. Alsea; May 23, 1931, H. k. Scullen, 19, gag; 19, inhs. Cannon Beach; June 10-18, 1927, Ic?, 39, cas; Id', inhs. Corvallis: June 9, 1930, Lorin? G. Hudson, Id', inhs; .April 29, 19,50, H. A.' Scullen, IcT, oac; May 15, 1925, Id', oac. Oak creek; May 4, 1934, Eldon Ball, 29; May 22, 1934, Dimick, Id', inhs; May 26, 1898, 19, oac. Philomath, Rock creek: May 1, 1934, R. E. Dimick, 19, oac Santiam road, Cash creek: July 20, 1910, 19, OAC. Siletz river: May 24, 1934, R. E. Dimick, 19, oac Tidewater: July 3, 1933, 19, OAC Warner mountains. Lake county: June 19, 1922, Id', 19, CAS. Washington.—Stabler: June 20, 1928, K. Gray, Id', oac; elevation 1500-2000 feet, 39, OAC; 2 9, INHS. Sialis occidens—new specie.s Stalls fuHginosa Davis (1903, p. 449) in part \nec PictetJ. MALE. —Length 11-13 mm. Similar in all respects to californica, except for the genital plate. Ninth sternite, lateral plates and terminal plate as described and illus- trated for cnlifoniica. Genital plate, fig. 49, wide at base and tapering to apex, basal por- tion curved upward above apex of terminal plate but not forming two bulbous lobes. FEMALE.—Apparently identical with that of californica. Holotype male —Wolverton, Sequoia Na- tional Park, Calif., altitude 7000-9000 feet: June r:., 1929, E. C. Van Dyke, cas. Allotype, female —Same data as for holo- type. Paratypes. California.— Id', nm. Wolver- ton, Sequoia National Park, altitude 7000- 9000 feet; June 23-25, Id', 19, cas; 1&, 19, INHS. Fallen Leaf lake. Lake Tahoe; July 2, Icf, cas; June 26, 19, cas. Placer county: June, Icf, INHS. Sierra Nevada: Crotch, Id', 19, MCZ. Nevada.—Reno: 1878, Morrison, Icf, 29, MCZ; IcT, 29, inks; Icf, 29, NM; Id', 19, kac; June 27, 1927, E. P. Van Duzee, 19, cas. This species is apparently restricted to a more southern distribution than cali- furnica. The specimens from Reno, Nevada, collected by Morrison were re- corded as fuUginosa by Davis. Sialis cornuta—new species MALE. —Length 12 mm. Color and gen- eral structure similar to joppa. Differs in details of abdomen and genitalia, figs. 7 and 19. Ninth sternite bandlike, clothed with onlii' moderately long setae. Lateral plates more or less ovoid, mesal margins somewhat angled and appressed for a dis- tance. Genital plate wide and deep, narrow- ing towards apex and produced into a pair of narrow hooks half as long as the plate ; these hooks, fig. 19a, projecting almost straight upward from the plate and scarcely curved. Terminal plate ovoid and flat, fig. 19b, its apex divided into two lobes by a narrow mesal incision, each lobe produced into a short, stout, hornlike process curved laterad. 70 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Alt. 3 FEMALE.—Similar in all respects to that of juppa, with the exception of the apical mesal projection of the eighth sternite, whicli is slightly longer. Holotype, male.—Horseshoe lake, Blue nuiuntains. Ore., elevation 7500 feet: July 26, 1929, H. A. Scullen, inhs. Allotype, female.—Same data as holotype. Paratypes. Alberta.—Nordegg: July 7-11, 1921, J. McDunnough, 2&, 29, cnm; !>, 29, INHS. Waterton: Julv 12, 1923, H. L. Seamans, Id', cnm; July 14, 1923, E. H. Strickland, IcT, cnm; 1 d', INHS. Idaho.—Moore's lake: July 10, 1907, J. M. Aldrich, IcT, inhs. Moscow: J. M. Aldrich, 19, inks. Utah.— Fruitland: March 20, 1937, F. C. Harmston, Icf, inhs. Red creek: March 20, 1937, F. C. Harmston, Id', uac. The male of this species is readily dis- tinguished by the hornlike processes on the terminal plate, but the female is difficult to separate from others of the califoniiai group (see key). Sialis hamata—new species MALE.—Length 12 mm. Color and gener- al structure as in joppa. Differs in details of abdom.en and genitalia, figs. 5 and 20. Ninth sternite bandlike, clothed with sparse, moderately short setae. Lateral plates more or less ovoid, appressed for a distance on the meson. Genital plates small from ventral aspect, but with a large re- curved hook at apex which is apparent only in lateral view, fig. 20a. Terminal plate Hat and round, the basal part produced at the apex into a thin flat neck, fig. 20b, at tlie end of which the genital plate articu- lates. This neck varies in length but is always as long as shown in the illustration. FEMALE.—Apparently identical with that of joppa except for the eighth abdominal sternite, fig. 52. This is emarginate along the apex except at the meson where a nar- raw projection juts forward. This pro- jection is on the same plane as the re- mainder of the segment. The bursa copu- latrix is membranous and amorphous. Holotype, male.—Logan, Utah: April 16, 1933, J. A. Meacham, inhs. Allotype, female.—Blacksmith Fork canon, Utah: July 9, 1935, C. F. Smith & G. F. Knowl- tOn, INKS. Paratypes. Alberta.—Lethbridge: Aug. 4, 1922, E. H. Strickland, Id', cnm. Waterton lakes: June 26-July 13, Id', 19, inhs; 39, CNM. Watertown: June 30, 1924, H. L. Sea- mans, Icf, cnm; Id', inhs; July 1, 1924, H. L. Seamans, 19, cnm. British Columbia.—Creston: May 28, 1926, A. A. Dennys, Id", cnm. Montana.—Lake Saint Mary, Glacier Na- tional Park: July 2, 1930, E. C. Van Dyke, Icf, CAS; 19, inhs. Spring Creek, Yellowstone National Park: July 15, 1923, A. L. Melandcr, 1 d', mcz. Oregon.—Warner lake, Lake countv, high tablelands: June 21, 1922, E. C. Van Dvke, 1 &, 19, CAS; Icf, INHS. Utah.— Parley canon, Salt Lake City: lunc 24, 1922, E. P. Van Duzee, Id", CAS. Washington.—Pullman: May 10, 1928, 1 cf, UM. Wyoming.—West Yellowstone: June 14, 1930, E. C. Van Dyke, 2d', cas. This western species is one of the few in the califoriilca group having a dis- tinguishing character in the female. The male is readily distinguished from other members of the genus by the "neck" on the terminal plate and the swan's-neck hook articulating with it. Sialis americana (Rambur) Semblis americana Rambur (1842, p. 447j. Sialis ferrupneus Walker (1853, p. 195). Sialis americana Hagen (1861, p. 188j; Banks (1892, p. 357); Davis (1903, p. 450). Prolosialis americana Van der Wheele (1909, p. 263; 1910, p. 75). MALE. —Length 12 mm. Yellowish orange with the antannae, eyes, tibiae and tarsi almost black. Abdomen, posterior half of head, palpi and margins of prono- tum suffused with blackish. Wings and veins yellowish orange. Head dull with fine reticulations, con- cave around branching of epicranial stem. Front wing with five to seven supernum- erary cross-veins in costal cell. Abdomen and genitalia as in figs. 10 and 22. Ninth sternite produced caudad into a fairly long, truncate sclerite, clothed with sparse but moderately long pubescence and covering bases of lateral plates. Lateral plates small and triangular, the postero- lateral portion angulate ; appearing as ap- pendages of the ninth sternite and not appressed on the meson. Genital plate ., forming a broad collar in front of terminal || plate, and bearing a pair of broad, straight '] arms. These appear in fig. 22a, so that at first glance they appear as appendages of the terminal plate. Terminal plate round, the margins clothed with long setae, the apex with a small, semicircular incision. FEMALE. —Size, color and general charac- teristics as in male. Seventh sternite, fig. 58, rectangular, neither larger nor more heavily sclerotized than the preceding seg- ments; produced into a convex area on the meson ; the entire segment together with September 1937 ROSS: NEARCTIC ALDER FLIES 71 the eighth clothed witli sparse but fairl\ long setae. Eighth sternite small and rec- tangular, the apical margin with a dia- inond-shaped shining area on the meson. Ninth sternite and bursa copulatrix indis- tinct in cleared specimens. Maryland.— Laurel: June 22, 1912, E. B. Marshall, Icf, nm. Ohio.— Kent: June 18-22, 1900, R. C. Osburn, 2c?', 19, osu; 2d', 19, inhs. The character of "black antennae' mentioned for americana by Van der Wheele and for ferrugineus by Walker in- dicate that both names apply to the species herein described. It is possible, however, that Rambur's name americana could apph to the species glabella described herein as new. At the present time it seems better to follow the synonymy of previous authors. Sialis glabella—new species MALE. —Length 12 mm. Yellowish orange with the following exceptions: mesal two-thirds of vertex dark reddish brown with the usual bars and spots yellow, forming a regular pattern, fig. 49 ; dorsum of abdomen dark brown ; sutures of mouth- parts, thorax and legs light brown; and antennae, tibiae and tarsi slightly darker and browner than body ground color. Head and pronotum smooth and polished, without any trace of sculpturing, clothed with ven,- fine short pubescence ; concave at branching of epicranial stem. Venation as in americana. Abdomen and genitalia very similar to those of americana with the following dif- ferences : Ninth sternite only two-thirds as long, lateral plates longer and closer to- gether, terminal plate identical, genital plate with a pair of long arms whose apical half is markedly narrowed, fig. 45. FEMALE.—Size, color and general struc- ture as in male, abdomen as in americana. Holotype, male.— Mt. Carmel, III.: May 28, 1884, sweeping (^acc. no. 1796), inhs. Allotype, female.—Same data as holotype. Paratypes. Illinois.— Muncie: June 16, 1908, H. E. Ewing, 19, INHS. This species looks very much like ameri- cana. but is easily distinguished from it b\ the shining, impunctate head, paler anten- nae and tibiae, and the narrowed genital arms of the male. Both records are points on the Wabash river drainage system. Sialis velata—new species MALE.—Similar to itasca, p. 72, in size. color and general structure. Ihc wings arc on the average darker and only rarcl\ present a banded appearance. Abdomen and genitalia, figs. 29 and 35. similar to itasca with these differences : ninth sternite with apical margin rounded ; lateral plates shorter, their apex broad and rounded and the lateral margin not angu- late ; genital hooks bending just below level of terminal plate and with a slender basal appendage which runs some distance from top prong; terminal plate longer, raised more than its width from the sclerite at its base. FEMALE.—Apparently identical with that of itasca. Holotype, male.— Houghton lake, Mich.: June 15-18, 19,H5, T. H. Frison, inhs. Allotype, female.—Same data, collected in coilit with holotype. Paratypes. .Alberta.— Medicine Hat: Mav 24, 1923, Icf, CNM. British Columbia.—Osovoos: Mav 20-21, 1923, C. B. Garrett, .^cf, 49, cnm; 3d', 19, INHS. Illinois.—Calvin: April 14, 1930, Frison & Ross, i(f, INHS. Charleston; April 23, 1932, Ross & Mohr, 1 cf, INHS. Dixon Springs: April 21, 1935, T. H. Frison, 2d', inhs. Dubois: .April 24, 1919, creek valley, 1 cf, inhs. Havana, Illinois river front: April 27, 1896, C. A. Hart, ^(f, inhs. Homer: May 6, 1911, Id', inhs. Mt. Carmel: April 19, 1932, Ross & Mohr, Id", inhs. New Columbia, Ciiftv creek: .April n, 1932, Ross & Mohr, Id', inhs. Parker: April 17, 1914, Id', inhs. Rock Island: Mav 10, 19.U, Ross & Mohr, Id', inhs; May 16, 1931, 20^, INKS. Shawneetown: .April 26, 1926, Frison & Auden, Icf, 19, inhs. Spring Grove, along Nippersink creek: May 14, 1936, Ross & Mohr, Sd', 129, inhs. Urbana: Mav 22, 1923, Id', inhs; April 26, 1890, C. A. Hart, at light. Id', inhs. Vienna; April 21, 1932, Ross & Mohr, Icf, inhs. Kansas.— Douglas county; .April 14, 1922, R. Guentert, 34d', 109, RU; 7d', SS, inhs; April 1923, R. H. Beamer, 3d', Ku. Manhattan: April 2, 1932, F. E. Whitehead, Id', kas; April 18, 1930, A. Audant, Id", kas. Mc- Pherson county: .April 16, 1932, Icf, kas. Onaga; May' ,^0, 1926, Id", inhs. Riley county; .April 29, Popenoe, Id', kas. Ma'ine.—Waldoboro: May 1902, I.ovell, Id', cu. Manitoba.^.Aweme: lune 14, 1912, N. Criddle, Id", cnm; May 27,' 1925, R. M. White, Icf, inhs; 19, cnm; June 13, 1926, N. Criddle, Id', cnm; June 4, 1926, R. D. Bird, i&, cnm; Criddle, Id', cu. Maryland.— Plummet's Island; .April 17- 22, 1903, W. V. Warner, 2d', 29, nm; April 22, 1915, T. C. Crawford, 2&, inhs; April 18, 1915, H. S. Barber, Id', nm; May, Id', 19, nm. Massachusetts.—Cambridge: May 28, 1900, S. Henshaw, 40^, mcz. Lake Cochicuate: May 28, Id", inhs. Wellesley: May 1895, .A. P. Morse, 5d", mcz. 72 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'ul. 21, Alt. 3 Michigan.—Ann Arbor, Washtenaw county: May 16, 1917, IcT, mm-/.. Detroit: May 5, H. G. Hubliard, Icf, mcz; May 27, 1897, 19, am; Icf, mcz; May, 2^", 19, mcz. Grayling, power dam on Au Sable river: June 17, 19.^5, T. H. Prison, Icf, inhs. Higgins lake, Craw- fonl county: June 19, 1932, G. Kelker, Icf, 29, MMZ. Houghton lake: Tune 15-18, 1935, T. H. Fri,son, 2 mating pairs, 220^, 489, inhs. Margurite lake: May 23, 1936, Prison & Ross, 2 mating pairs, 391 cf, 6629, inhs. Mio, along Au Sable river: May 21, 1936, Prison & Ross, 35cf , 39, INHS. Omer, along Rifle river: May 21, 1936, Prison & Ross, Icf, 19, inks. Wash- tenaw county: May 22, 1930, lrf',MMz. Minnesota.— Big Cormorant lake: May 14, 1900, R. C. Osborn, !&, 29, osu. Coon creek: May 20, 1933, D. J. Pletsch, 2cf, um. Itasca county: Icf, um. Itasca Park: May 30, 1932, C. H. Hofl^man, 14c?, 19, um; Scf, inks; June 13, 1928, L. W. Orr, 3d', 29, um; June 9, 1934, W. A. Riley, 19, um. Missouri.—Columbia: April 21, 1905, Icf, INHS. New H/iMPSHiRE.—Three-mile island: June 2, Icf, MCZ. New York.—Cortland county, Labrador lake: May 14, 1921, Id', cu. Crosby, Yates county: May 18, 1918, Icf, cu. Cranberry lake: June 23, 1919, J. C. Clark, Icf, cu; June 26, 1920, C. J. Drake, Icf, inhs. Litchfield: May, 1903, Icf, AM. Oswego: May, 1894, 1 cf, NM. Peru: May, 1914, 2 cf , cu. Stanley: May 1920, Icf, cu. Syracuse: Cook & Collins, 1 cf, NM. Westport: May 1921, 1 cf, inhs; May 20, 1922, 4cf , 19, am; Icf, 19, inhs. North Dakota.— Pargo: June, Icf, inks. Ontario.—Casselman: May 23, Icf, cnm; April 21, 1904, Icf, CNM. Jock'river: May 23, 1927, G. S. Walley, Icf, inhs. Maitland: June 12, 1931, L. J. Milne, 4cf, 119, cnm, Icf, 19, inhs. Ottawa, Rideau river: May 27, 1930, L. L Milne, Icf, cnm; June 9, 1920, J. Mc Dunnough, 2cf, cnm; May 29, 1920, J. Mc Dunnough, 2cf, 39, cnm; Icf, 19, inhs. Rat Portage island: June ,1905, J. C. Bradley, 1 cf , cu. Sand lake: " July 3, 1926, P. P. Ide, 3cf , cnm. Sioux Lookout: June 25, 1929, J. Russell, Icf, CNM. Southampton: June 20, 1931, G. S. Walley, Icf, CNM. Trenton: May 5, 1900, 1 cf , CNM. Quebec— Knowlton: June 21, 1929, L. J. Milne, Icf, CNM. Lachine: June 8-9, 1926, F. P. Ide, 11 cf, 39, cnm. La Prairie: June 14, 1927, G. S. Walley, 4cf, 49, cnm; Icf, 39, inhs; June 9, 1926, F. P. Ide, 2cf , cnm. Saskatchewan.—Scudder, icf, 19, inhs. Saskatchewan river: Icf, mcz. Texas.— Kerrville: March 24, 1906, P. C. Pratt, 1 cf, INKS. Virginia.—Great Palls: April 19-30, 6cf, mcz; May, 1 cf , nm; May 2, 1916, 1 cf , nm. Washington, D. C.—May, Ashmead, 2cf, nm; Apr. 3, 19, nm; Apr. 20, Icf, mcz; Apr.29, Icf, NM. West Virginia.—Millville: Apr., 1921, Icf, INHS. Wisconsin. — Washington Island, Door county: June 7, 1905, Icf, 19, mcz. Sturgeon bay; June 7, 1929, A. Granovsky, 2cf , 69, uw; Icf, 29, inhs. Madison: May 1934, 1 cf, uw; May 31, 1912, A. C. Burrill, Icf, uw. Lake Mendota: June 7, 1910, J. G. Sanders, Icf, uw. Trout lake: June 1, 1934, H. L. Chada, Icf, uw. Sialis itasca—new spelie.s MALE.—Length 11 mm. Black with these exceptions : head with hars and spots, narrow margin around eye and malar space orange. Wings dark brown with apical two-thirds varying from slightly paler to completely hyaline. Specimens of this type present a striking banded appearance when the wings are spread. GENERAL STRUCTURE.—Dorsum of head dull with coarse and abundant sha- greening. Vertex usually concave along meson, but sometimes robust and even slightly convex. Front wing with about 10 accessory cross-veins in costal area, re- mainder of venation normal. Abdomen and genitalia as in figs. 28 and 34. Ninth sternite narrow, apical margin angular. Lateral lobes long, their lateral margins more or less angular ; apex blunth pointed so that the apical portion is some- what triangular. Genital plate collarlike, situated below terminal plate, and giving rise to a pair of long, bent arms, fig. 28a, projecting forward almost to the ninth sternite ; the two arms are closely appressed, usually appearing as one; each arm angles forward just above level of terminal plate and at its base has a lobe thicker than the arm and running very close to it. Terminal plate, fig. 28b, with a wide angular incision at apex ; the plate rising less than its width above the sclerite at its base. FEMALE.—Length 13 mm. Color and general structure as in male. Abdomen and genitalia as in fig. 54. Seventh sternite wider than long, only slightly arcuate at ape.x. Eighth flat, wide and narrow, with a median shallow de- pression. Apex of bursa copulatri.x sclero- tized and rounded, with a long straight fingerlike process on the ventral side at extreme tip, figs. 46, 54. Holotype, male.—Momence, 111., along Kan- kakee river: June 1, 1937, B. D. Burks, inks. Allotype, female.—Same data as holotype. Paratypes. — Illinois.—Charleston: June 19, 1931, H. H. Ross, INHS. Maywood, DesPlaines river: June 7, 1912, 1 cf , inks. Momence: same data as holotvpe, 2cf, 19, inhs. White Heath: June 9, 1929,' C. O. GofT, Icf, inhs; June 18, 1906, woods, 1 cf , INHS. W'hite Pine State Park: May 30, 1936, Ross, 1 &, inhs. Kansas.—Manhattan: May 20, 1925, R. E. Sears, Icf, inhs. September 1937 ROSS: NEARCTIC ALDER FLIES 73 Michigan.—Douglas lake: July 4, 1927, L. K. Gloyd, IcT, inhs. Missouri.— Bryant's Point: Mav 13-15, 1915, P. Bartsch, la", inhs; 2d', nm. New York.—Cranberry lake: July 8, 1920, C. J. Drake, Icf, cu. Ithaca: June 20, 19<)7, Icf, inhs; June 12, 1914, Icf, inhs; June 12- 14, 1915, 2c?',cu; 2 cf, inhs; June 17, 1916, Icf, ci; June 25, 1916, IcT, cu; June 16, 1915, Icf, cu; 2c?', inhs; June 12, 1913, IcT, cu; May 18, Icf, cu. Rochester Junction: June 9, 1914, M. D. Leonard, Icf, cu. North Dakota.— p'argo: June 3, 1901, R. C. Osborn, 1 cf , osu. Ohio.—Huron: June 24, 1914, 1 cf, 139, cu; 1 cf, 49, INHS. Marietta: icf.MCz. Ontario.—Algonquin park: June 18, 1922, I. McDunnough, Id", cnm. Britannia: June Z^, 1920, G. Beaulieu, 3cr, 29, cnm; 2(f, 29, inhs. Ottawa West: June 21, 1920, C. B. Hutchings, Icf, cnm; Icf, inhs. Pennsylvania.—Candy Hill: May 28, Icf, INHS. Harrisburg: Mav 30, 2cf, inhs. West Chester: May 19, 1924, Icf, cu; Icf, inhs; 1 cf , ANS. Quebec—Lacolle: July 5, 1928, G. H, Hammond, Icf, cnm. Laprairie: June 17, 1925, F. P. Ide, 3cf , 29, cnm; 2cf , 29, inhs. Virginia.—Dyke: May 28, 1915, W. L. McAtee, Icf, nm. Great Falls: May 25, N. Banks, iOcf , mcz; 4cf , inhs; June 3, Icf, Mcz; |une 18, 1 cf , mcz; June 5, 1 cf , mcz. Mt. Ver- non: June 6, 1915, W. L. McAtee, Icf, inhs. Washington, D. C.— F. C. Pratt, Icf, nm. Sialis infumata Newman Siri/ii infumata Newman (1838, p. 500j. MALE.—Similar in size, color and genera] structure to velala and itasca. Differs in genitalia as follows, figs. 30 and 36: ninth sternite narrow and slightlj- angulate at apex; lateral lobes long, the apical fourth constricted and forming a large round knob ; genital hooks long and slender, bend- ing at half the height of the terminal plate, the appendage near their base ovate and short, no longer than a third of the hori- zontal portion of the hook ; terminal plate twice as high as wide, its sides convex and narrowing towards apex, the latter with a shallow, narrow incision on the meson. FEMALE.—Similar to that of velata, dif- fering only in the structure of the eighth Sternjt^. hg. 60. This is longer and rec- tangular, with a narrow V-shaped depres- sion extending along the meson of the entire segment. The halves have the apical half somewhat raised into a lobe and the pos- terior half flat. Holotype, female.—Trenton Falls, N. J.: Doubleday, bm. Allotype, male.—Wilmington, 111., along Kankakee river: May 17, 1935, H. H. Ross, inhs. Illinois.—Algonquin: May 12, 1906, W. A. Nason, 2cf, 19, inks. Cedar lake: 3cf, 19, inhs; 3cf, osu. Kaston, central ditch: May 1, 1914, icf, INHS. Galena: Icf, 19, mcz. Oakwood: April 26, 1936, Eugene Rav, 2cf, INHS. Rantoul: April 24, 1929, Prison & Ross, Icf, INHS. Wilmington: May 12, 1935, Prison & Ross, 3cf, iNHs; May 17, 1935, H. H. Rcss, 30^, 19, INHS. Kansas.—Manhattan: April 30, 1933, D. E. Musser, 2cf , inks; April 7, 1930, R. H. Painter, Icf, KAs; May 15, 1933, Icf, kas; Sept. 10, 1932, M. W. Allen, 2cf, kas. Michigan.—Vassar branch of Cass river: May 20, 1936, Prison & Ross, 1 cf , inhs. New York.—Ithaca: May 3-25, 4cf, 99, inhs; 2cf, 159, cu; inlet valley. May 3, 1913, Icf, cu. Syracuse: Cook & Collins, Icf, nm. Ohio.—Columbus: April 23, 1899, R. C. Osborn, 1 cf , osu. Pennsylvania.—Harrisburg: May 11, 1909, Icf, INHS. Manayunk: April 26, 1 cf, ans. The identity of this species is still a trifle uncertain. D. E. Kimmins of the British Museum has kindly compared specimens with the female type and says that it agrees most closely with this determination. The differentiation of the females of the in- 1utnata-itasca-velata group, however, is not as definite as might be w-ished. Mr. Kim- mins, however, cleared the abdomen of the type, so that the present treatment is as satisfactory as possible under the circum- stances. The bibliography of this species includes only the original description. The other references to the species in literature can- not be placed with certainty due to the confusion of so many species under this name by various authors. Sialis concava Banks Siaiis concava Banks (1897, p. 22) MALE.—Similar in size, color and general structure to infumata and itasca. Dift"ers in genitalia as follows, figs. l>3i and 37 : lateral plates smaller, more or less triangu- lar, flat and angled at apex ; genital hooks, fig. 33a, long, slender for their whole length, angled at half or less the height of the terminal plate, and without an appen- dage at their base ; terminal plate, fig. 33b, long, slender, tapering almost to apex, which is slightly widened and beset with a cluster of fairly long setae. FEMALE.—Unknown. Holoytpe, male.— Ithaca, N. Y., mcz. Maryland.— Icf, inhs. New York.— Ithaca: May 29, 1913, Icf, INHS. Ontario.—Power Glen: June 25, 1926, G. S. Walley, Icf, cnm. 74 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'ol. 21, Art. 3 The tj'pe has the genitalia expanded so that the parts are readily seen. Sialis hasta—new species MALE.—Similar in size, color and general structure to inluniata. Differs in genitalia as follows, figs. 31 and 38: ninth sternite hroad, apical margin evenly rounded; lat- eral plates broad, their apex wide and evenly rounded; genital hooks, fig. 31a, hroad at base, tapering beyond bend to a point, very low, the outer margin of the bend angular; appendage at base of hooks triangular, short and with an angular apex ; terminal plate quadrate, fig. 31b, each lateral corner prolonged into a long, straight apical process, these processes sur- mounted by a tuft of setae and separated by a distance almost equal to their own length. FEMALE.—Similar in color and general structure to male. Genitalia very similar to those of infuiiiata, fig. 54, differing as follows: seventh sternite with only apical half sclerotized, apical margin broadly and shallowly emarginate, eighth sternite with antero-lateral portions slightly more round- ed than in fig. 54. Holotype, male.—I.ovells, Mich., along Au Sable river: May 22, 1936, Prison & Ross, INHS. Allotype, female.—.Same data as holotype. Paratypes. Michigan.—Hale, along Au Ores river: May 21, 19,36, Fri.son & Ross, Icf , INHS. Lovells: 4cf , 89, same data as holotyvie; May 24, 19,36, J. W. Leonard, Id', 159, inhs. Whittemore along Johnson creek; May 21, 19,36, P'rison & Ross, 2c?', inhs. Pennsylvania.—Allegheny county, Icf, cm; 1 &, INHS. Washington county, 1 cf, cm. Sialis mohri—new species MALE.—Similar in size and color to infumata. Differs in general structure as follows: median area of vertex concave, velvety in appearance due to fine setae and punctures ; costal area of front wing with six to 10 accessory cross-veins, averaging seven or eight. Abdomen and genitalia as in figs. 32 and 39. Ninth sternite angular on meson, not very long; lateral lobes broad, narrowed at apex to a rounded point ; genital plate, fig. 32a, broad at base, with a long, thin, curving blade three times as long as the basal portion ; terminal plate, fig. 32b, more or less heartshaped, bearing a pair of long arms at apex which come off at right angles to the main sclerite, and curve slightly upward; each arm is stocky at its base and tapers to a fine point, is ver\ heavily sclerotized, and sinuate, fused with each other at base, and beyond that sepa- rate. FEMALE.—Similar to male except for genitalia and larger size. Abdomen and genitalia, fig. 56, very characteristic of species: seventh sternite as for genus; eighth very narrow on meson, the lateral portions more or less triangular ; apparent ninth sternite sclerotized, fitting within the cut-out margin of the eighth, having a sclerotized carina along the meson at apex, the entire segment somewhat diamond shaped. Holotype, male.—Boulder Junction, Wis., on Trout river: June 20, 19,34, Prison & Mohr, INHS. Allotype, female.—Same data as holotype, and collected in coilti with it. Paratypes. Connecticut.—New London: June 23, 1917, R. C. Osborn, 2&, osu. Illinois.—Algonquin: May 20, 1906, W. A. Nason, 5d', 29, inhs; May 29, 1909, 19, inhs. Antioch; Channel lake: June 5, 1919, T. H. Prison, 2cf, 29, inhs; May 16, 1936, Ros.s & Mohr, 2cr, 99, inhs. Near Cooperstown, Illi- nois river: May 20, 1932, Ross & Mohr, 1 &, INHS. Dubois: April 24, 1914, Creek valley, ScT, 79, INHS. Pox Lake, along lake: May l.S, 1936, Ross & Mohr, 214^", 609, inhs; May 28, 1936, Ro,ss, 2cf , 109, inhs; May 28, 1936, Ro.ss, 2cf,iNHs. Glenn Ellyn: May ,30, 1908, W. J. Gerhard, 2cr, fm; Icf, inhs. Grays lake: May 26, 1936, Ross, i&, 79, inhs. Havana, Illinois river: June 3, 1933, Mohr, Icf, inhs; May 4, 1895, Hart, 1 cT, 19, inhs; May 8, 1932, Mohr, Icf, 89, inhs; May, 1895, 19, inhs; May 21, 1895, 29, inhs; M.ay 21, 1932, Ross & Mohr, 3c?, 89, inhs; April 27-30, 1896, C. A. Hart, 2cf , 39, inhs. Henry, Lake Senachwine: May 30, 1932, D. H. Thompson, Id", 39, inhs. Kankakee: June 6, 1935, Ross & Mohr, Id", inhs. Lake Porest: May 1905, J. G. Needham, 1 cf , 19, cu. Meredosia, Illinois river: May 15, 1934, Prison & Mohr, 2&, 39, inhs. Paris: 1931, Id', INHS. Pistakee lake: June 12, 1936, Icf, 19, inhs. Rockford: W. Bebb, 1 d", inhs; June 10, 1897, 19, inhs. Rock Island, near Rock river: 1863, Walsh, 19, mcz; 19, inhs; May 18, 1934, Ross & Mohr, 19, inhs; Walsh, 19, MCZ. South Chicago, Calumet river: June 9, 1880, 39, INHS. Wilmington, Kankakee river: May 17, 1935, H. H. Ross, Id", inhs. Indiana.—Wolf lake: May 26, 1912, A. B. Wolcott, i(f, 19, fm; 2d', inhs. Kentucky.—Near Mammoth Cave: May 2, 1874, J. G. S., IcT, mcz; Id', inhs. Massachusetts.—Cambridge: May 28, 1900, S. Henshaw, 2&, mcz; IcT, kas. Pram- ingham: May 23, 1930, C. A. Prost, Ic?, inhs. Haverill: June 7, 1866, 19, mcz. Minot county: June 10, 1871, Sharon, 2d', 19, mcz. Holliston: May, i&, mcz. Wellesley: May 1900, A. P. Morse, 8cf', 39, mcz. Michigan.—Ann Arbor, Washtenaw county: May 22, 1919, P. M. Gaige, Id', mmz. Bryant September 1937 ROSS: NEARCTIC ALDER FLIES 75 bog: July 12, 1924, H. B. Hungerford, 19, ku. Cedarville: June 1929, IcT, cm. Cheboygan county: July 4 and 24, 1935, D. S. Shetter, IcT, 19, MMZ. Clinton along Raisin river: May 19, 1936, Prison & Ross, Id", inhs. Detroit: Tune 1874, Icf, 49, mcz. Douglas lake: ]u\\- 3, 1927, L. K. Glovd, 3cf , kas: July 8, 1929, H. B. Hungerford, 59, ku; 29, inhs; July 20, 1926, H. Br Hungerford, 29, ku; June 6, i925, Charles Martin, Icf, 19, ku; Icf, 19, inhs; June 22-25, 1926, Charles Martin, 39, ku; June 25, 1928, Charles Martin, 1^, ku. Fonte- nalis Run, Burt lake: July 7, 1926, H. B. Hungerford, Icf , inhs; 19, ku. Houghton lake: June 15-18, 1935, T. H. Prison, 1 mating pair, 1886", 1659, INHS. Mill lake, Washtenaw county: May 24, 1919, R. F. Hussey, 1 d' mmz. Mio, along Au Sable river: May 21, 1936, Prison & Ross, 6cf, 19, inhs. Portage lake, Washtenaw county: May 30, 1905, N. A. Wood, Scf, 39, MMZ. Minnesota.— Bemiji: June 19, 1932, J. Karlovich, 2cf, inhs. F'rontenac, shore of Lake Pepin: May 25, 19.?0, W. C. Stehr, 5d<, 19, um; 2&, 19, inhs; Mav 29, 1930, C. F.. Mickel, 2d', 29, um: May 22, 1932, Theodore Olson, 89, um; 29, inhs. Goodhue countv: May 25, 1930, Carl T. Schmidt, 60", um. Hennepin county: May 30, 1921, A. T. Hertig, 29, UM. Lake Superior: Icf, 19, um. Minne- apolis: June 7, 1916, Id", inks. Ramsey county. Lake Johonna: Mav 17, 1922, Wm. ¥.. Hoffman, 29, um; June 17, 1920, H. H. Knight, Id", UM. Red Lake county: Tune 12, 1920, Jonson, 19, um. Staples: Tune 22, 1924, C. B. I'hilip, 29, UM. New F^ngi.and.—A. .'\gassi7., 19, inhs. New Jersey.— Lakehurst: May 24, 1914, R. C. Osborn, Icf, osu. Lake Hopatcong: Mav 30, 2d", 19, am. Newfoundland: Mav, R. C. Osburn, 19, osu. New York.—Nepperhan: May 27, 1905, 2^, cu; Id", INHS. Mosholu: 6d', 49, am; 1 'mph. A series of males and females of this species was reared at Urbana from nymphs collected in the White river at Rogers, Ind., June 1936. Acroneuria perplexa — new species MALE.—General color light to dark brown. Head, fig. 65, with a yellowish brown transverse area extending between compound eves across ocellar region, most of area anterior and posterior to this transverse patch a dark brown. Pronotum light brown, with lateral margins and raised rugosities or embossings much darker. Legs mostly light brown, with a small conspicuous black band at tip of each 80 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 3 femur and at base of each tibia. Antennae and cerci brown. Head scarcely wider than pronotum ; three ocelli arranged in a triangle, and lateral ocelli closer together than to median ocellus and slightly closer to each other than to inner margins of compound eyes. TIPS OF SUBGENITAL PLATES 5 ABDOMINAL STERNITES Fig. 65. — Acroneuria perplexa. Pronotum, fig. 65, approximately quad- rangular, much broader than long, hind angles rounded, front angles rather sharp, rugosities arranged in a definite pattern and corresponding well with color pattern a in nymph ; median longitudinal depressed area narrow. Wings long, extending well beyond tip of abdomen ; membrane hyaline with veins dark brown ; venation somewhat variable in regard to numbers of cross-veins but otherwise essentially typical for the genus, several cross-veins in forewing in area be- yond the cord, and veins 9-1 1 of hind wing reaching margin of wings variable. Abdomen, fig. 65, without special struc- tures except for terminal segments. Tenth tergite not cleft ; genital hooks prominent, recurved upwards, narrow for most of length and tapering to a point ; small spin- ulae numerous on ninth and tenth tergites; ninth sternite with a small, slightly trans- versely oval padlike disk. Two groups of gill remnants are on the side of each thoracic segment and on upper part (usually concealed) of subanal lobes, thus correlating with gills of nymph. Length to tip of wings 27 mm. ; lengtli to tip of abdomen 18 mm. FEMALE.—In general very similar to the male as here described, but somewhat larger. Differs from male in important characters as follows : eighth abdominal sternite, fig. 65, with posterior margin somewhat produced over ninth sternite, in most specimens with posterior margin of subgenital plate rounded but sometimes slightly truncate or notched. Holotype, female.—Petersburg, Ind., White river: June 16, 1936, Mohr & Burks, reared from nymph. Allotype, male.—Petersburg, Ind., White river: June 8, 1936, Prison & Mohr, reared from nymph. Paratypes. Illinois.—Shawneetown, at light: June 21, 1927, Prison & R. Glasgow, 19. Indiana.—Rogers, White river: May 26-27, 1936, Prison, Ross & Mohr, 39, reared. Peters- burg, White river: June 4-24, 1936, prison, Mohr & Burks, Icf, 49, reared. Ohio.—Ironton: June 1, 1899, 19. Pennsylvania.—Philadelphia, at light: June 15, P. Haimbach, 19. Washington, D. C: 19. The nymph of this species has not previ- ously been recognized and therefore its description is now presented. Most of our adult material has been obtained by rearing and therefore the association of the adult with nymph and males with females rests upon a reliable foundation. NYMPH.—General color of head, thorax and abdomen pale whitish yellow with dark markings as in illustration, fig. 66. The most important dark markings are the broad patch on head, pattern of pronotum and the band on basal half of each abdomi- nal tergite. The light-colored W-shaped mark anterior to median ocellus and two light spots associated with each lateral ocellus on the dark part of the head are also prominent. Cerci and antennae pale whit- ish yellow. Head with three ocelli arranged in a triangle, lateral ocelli much closer to each other than to median ocellus. No occipital Scptcmlx-r \'IM PRISON: DESCRIPTIONS OF STONEFLIES 81 iidf;c. Labium and maxillae approximatel) the same as described for other members of the genus. Proiiotum about twice as wide as long, all angles well rounded. Legs, tarsal seg- ments and cerci approximately the same as described for other species of the genus. Two pairs of gill tufts on each thoracic segment placed as in Acrotieuria internatn (Prison 1935a, fig. 266). No submental gills. Caudal gills at apex of abdomen are present. Approximately mature specimens with a body length, exclusive of appendages, of about 22 mm. Nymphs and exuviae.—All from the White river, near Rogers, Portersville and Peters- burg, Ind., collected trom one to several weeks prior to emergence ot reared adults recorded above. This species has been described as ne\\" with full knowledge that a few specimens of the same species in other collections ha\ e been determined in the past as peimsyl- rniiica (Rambur). This specific name has been applied to so many different species, however, and so much doubt exists regard- ing the important structural details of the type, if still in existence, that clarity and certainty in diagnostic work cannot be ob- tained at the present time by the use of this old name. It has seemer best, therefore, in \iew of the fact that my specimens of male, female and nymph are reliably associated upon the basis of reared material, to name my specimens as new. If ever the type of pi'iinsyh'anica Rambur is definitely proved to be the same as the species I am now nam- ing, then my name can be shelved in syn- onymy. Meanwhile the present species will not have been confused with other forms going under the same name. In my Illinois report (Frison 1935a, p. 395 ) a single adult female specimen of this species from Shawneetown, III., June 21, 1927, was erroneously recorded as iib- norrnis. Due at the time to the lack of additional Illinois material and knowledge of the nymph, the observable difference in the subgenital plate was considered as an instance of unusual variation. This same specimen, too, was named by Professor P. W. Claassen in 1928 as peiinsylvanica Rambur, indicating that part or all of his specimens recorded as peiinsylvanica may be the species here described. Evidently, based upon its rareness in this state, Illinois may be on the extreme limits of its range. That some slight variation exists in the shape of the subgenital plate, fig. 65, is evident from my reared specimens. The posterior margin of this plate in most of my specimens is rounded, but in one specimen it is slightly notched, and in another somc- wh.at truncate. ^'l^,^ Fig. 66.—Nymph of Acroneuria perplexa. My experience with the identification of Acroneuria to date is such as to warrant the statement that the fundamental units or species are not always easy to recognize. In Illinois there are six species as proved by important structural characters, associ- ation of reared males and females, kinds of nymphs, etc. Certainty in recognizing these species has come only through the rearing of adults from distinctive nymphs. This suggests that further revision of the genus and description of species should await the association of adults with nymphs bv rearings and field work. 82 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 3 Togoperla kansensis (Banks) Pcrld kansensis Banks (1905, p. 56). Origi- iiiil description. Togoperla sp. a, Prison (193Sa, p. 414). Nymphal description. In the report on stoneflies of Illinois (Frison 1935a) a nymph was figured as ""Togoperla sp. a" based upon several small specimens collected at Alton and Grafton, 111., on the Mississippi river. At that time 3 TERMINAL ABDOMINAL TERGITES Fig. 67.— Togoperla kansensis. it was stated, "It may be that this is the nymph of Perla kansensis Banks which is known from Kansas." Discovery of this nymph in numbers in the White river, Ind., has permitted the rearing of both sexes of the adult and the definite association of this nymph with kansensis Banks. Since illustrations of the adults were not included in my 1935 report, figures of the most important structural features are presented here in fig. 67. The specific placement of this stonefly necessitates a key for separation of the adults of our two Illinois species of this genus as follows: KEY TO SPECIES OF TOGOPERL.'V Males Eighth abdominal tergite (Frison 1935a, fig. 206) with its posterior margin produced backwards into a definite lobe; genital hooks of tenth tergite with ends rounded . media (Walker) F^ighth abdominal tergite, fig. 67, without a produced lobe on posterior margin; genital hooks of tenth tergite with ends pointed. . kansensis (Banks) Females Subgenital plate of eighth abdominal sternite (Frison 1935a, fig. 254) but slightly produced backwards over ninth sternite media (Walker) Subgenital plate of eighth abdominal sternite, fig. 67, considerably produced backwards as a triangularly shaped projection over ninth kansensis (Banks) No Illinois records for this species have been obtained in addition to those already recorded (Frison 1935a). My Indiana records are as follows: Indiana.—Petersburg, White river: May 10, 1936, Frison & Mohr, Icf, reared; June 3-4, 1936, Mohr & Burks, 12 cT nymphs, 139 nymphs, 6 small nymphs, 3 exuv.; June 9, 1936, Frison & Mohr, 19, reared; June 17-20, 1936, Frison & Mohr, 7cr, reared; June 22-27, 1936, Frison & Mohr, 39, reared, i&, reared; July 1-6, 1936, Frison & Mohr, 1 d', 39, reared, 2cf, reared. Portersville, East Fork river: June 3, 1936, Mohr & Burks, 3cf nymphs. Rogers, White river; May 13, 1936, Mohr S: Burks, 1 small nymph. Hydroperla varians (Walsh) Perla varians Walsh (1863, p. 364). Original description (cf, 9). Hydroperla varians Frison (1935a, p. 426). Male description and records. In my previous treatment of the Illinois stoneflies (1935a) I did not have available for illustration the female of this species, and its nymph was unknown. In the origi- nal description of varians by Walsh the female was recorded but the description of it might well have applied to either of the other two Illinois species of this genus. Recently I have studied a female specimen belonging to the Academy of Natural Sciences of Philadelphia, which was named by Walsh as varians, and two specimens, male and female, reared from similar nymphs collected in the White river near Rogers, Ind. This reared female agrees with the female specimen now in the Phila- delphia Academy, which was named by Walsh, and therefore establishes the correct association of the male and female of this species in his original description. d" HEAD AND PRONOTUM Fig. 68. — Hydroperla varians. The subgenital plate and head, not illustrated in 1935, are shown in fig. 68. Hydroperla varians seems to be best dis- tinguished from the females of the other Illinois species {crosbyi and harti) by the subgenital plate covering a much greater area of the ninth sternite (Frison 1935a, figs. 324 and 325). September 1937 PRISON: DESCRIPTIONS OP STONEPLIES 83 Since the nymph, fig. 69, has not been previously recognized a description of it is given as follows: NYMPH.—General color of head, thorax and abdomen pale yellowish with brown markings. Prominent uf the brown mark- ings are the dark area between ocelli, the dark ring connecting dark area between ocelli and compound eyes, the dark border of pronotum, and pattern of meso- and metathorax. Antennae, legs and cerci pale yellowish. Head with three ocelli forming a tri- angle with distance between lateral ocelli longest ; lateral ocelli situated about on a line through front margin of compound eyes. No real occipital ridge but posterior margin of the dark ring connecting dark area between ocelli and compound eyes is lined with short stout spinulae. Labium and maxillae practically the same as those of H . harti and H. crosbyi. Pronotum about twice as wide as long, all angles well rounded, fringed with short setae and stout spinulae on anterior and posterior margins; marginal groove well developed on the anterior and posterior margins and weakly so on sides. Short stout setae delineating the dark markings (jn meso- and metathorax. Legs somewhat flattened, posterior mar- gins of femora, tibiae and tarsi with a fringe of long fine setae. Abdomen with short stout spinulae very prominently lining posterior borders of tcrgites and also with scattered spinulae on tergites in addition to short hairs. Cerci long, many segmented, segments progres- sively longer apically, a longitudinal row of long fine hairs in middle of segments from base to apex. Submentum with a small fingerlike gill at each outer posterior corner. Body length, exclusive of appendages, 15 mm. Indiana.—Rogers, White river: April 21, 19,?6, Prison & Mohr, 1 nymph. Portersville, East fork White river: June 3, 1936, Mohr & Burks, exuv. Petersburg, White river; June 3, 1936, Mohr & Burks, exuv. Rogers, White river: .'^pril 21 and 30, 1936, Prison & Mohr, exuv. A revised key for the Illinois nymphs of this genus is as follows: KEY TO NYMPHS OF HYDROPERI.A ^r»**-t> Fig. 69.—Nymph of Hydroper/n varians. so that abdomen appears distinctly transversely banded (Prison 1935a, fit;. 329) crosbyi (N. & Cj Uorsal segments ot abdomen not thus dis- tinctly banded 2 Dorsum of head with a round open eyelike spot ringed with brown back of epicran- ial arm between compound eye and lat- eral ocellus on each side ot head; ab- dominal tergites without brown spots except those associated with stout spinulae varians (Walsh) Dorsum ot head with a wide dark trans- verse band crossing head anterior to lateral ocelli, no open eyelike spots; ab- dominal tergites with some small dark spots in addition to those associated with stout spinulae harti I'Vison 1. Dorsal segments of abdomen with basal portions dark and apical portions light ADDITIONS TO NEARCTIC PLECOPTERA NOT KNOWN IN ILLINOIS Nemoura oregonensis Claassen Nemoiira oregonensis Claassen (1923, p. 2,S8). Original description. This species was originally described from a single male collected "June 21, 1922, Blitzen Valley, Harney county. 84 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'l)l. 21, Art. 3 Oregon," and has not been recorded since. A series of specimens of this species, includ- ing the previously undescribed female, have been recognized among an assortment of material sent to me for determination by entomologists of the Oregon Agricultural College. FEMALE.—Similar in most morphological features to the male. Wings, fig. 70, with the same pattern as for the male. Seventh abdominal sternite, fig. 70, with posterior with middle of compound eyes, median ocellus located somewhat anterior to a line between front margin of compound eyes. Wings, fig. 7 1 , stained with brown except for clear spots in scattered areas ; subcosta ending before cord. Ventral cervical region without gill remnants. Fig. 70. — Neinoio oregoneiisis. margm produced bulblike, over eightn sternite. Four fingerlike gill remnants in ventral cervical region. Allotype, female.—Corvallis, Ore., Oak creek: Apr. 1.^, 1934, E. E. Ball. Oregon.—Corvallis; Apr. 10, 1933, R. E. Dimick, 19; Apr. 16, 1931, Itf'; Dixon creek, March 10, 1935, R. E. Dimick, \&; Oak creek, March 18, 1934, R. \V. Prentiss, 19, and March 31, 1934, E. K. Ball, IcT, and Apr. 7, 1934, E. E. Ball, 19. Benton county. Woods creek: Apr. 11, 1936, R. E. Rieder, ' other structures ; subanal lobes modified into a long produced lobe, curving upward beneath cerci ; cerci sclerotized, pincher shaped, main upper prong with small tooth at base and tip strongly pointed, main lower prong similarly shaped, tips of two main prongs widel\' divergent, base of cerci from which prongs project narrow ; ninth sternite produced into a short, feebly indented plate. FEMALE.—Similar in most morphological features to the male. Terminal and ab- 9 ABDOMINAL STERNITES Fig. 72. — Leiiclra forciptUd. dominal sternites with a well-developed subgenital plate, the lobes of which are widely divergent. Dorsal tergites of ab- domen 1 through 3 darkly sclerotized, through 8 mostly membranous with a median longitudinal darkly sclerotized stripe, ninth and tenth tergites darkU sclerotized. Holotype, male.— Corvallis, Ore. Allotype, female.—.Same locality as holo- type. Paratypes. Oregon.—Same locality as holo- type, i&, 19. ,^lsea Mt.: March 18, 1936, ]. Schuh, IcT. This species is closeh' related to L. oc- riiletitalis Banks and to L. purcellaiia Neave. It differs from both in the shape of the cerci. In purcell/ina the cerci have the upper projection or prong truncate and in occidentalis the upper prong is much longer than the lower and its base is more elongate. Eucapnopsis brevicauda (Claassen) Capnia brenicauda Chiassen (1924b, p. 55). Original description. Eucapnopsis brevicauda Neave (1934, p. 5). This species has had a short but interest- ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 3 ing history tu d;ite. The original lU'scrip- tion was based upon females, the male being unknown at the time, and placed in the genus Capniti. Needham & Claassen (1925) recognized the short cerci as aber- rant for Ciifiniti and noted the assignment of brevicauda to Eucapnopsh Okamoto (1922); the latter, however, they con- sidered a sub-genus. Since then Neave (1934) has found this species in British Columbia and has de- d" ABDOMINAL SEGMENTS 8 ABDOMINAL STERNITES Fig. 73. — Eucapnopus hievicauda. scribed the previously unknown male. It has a combination of characters which caused him to consider Eucapnopsh as a valid genus and with this conclusion the writer is in agreement (1935a). Illustrations, records and notes pertain- ing to this species are given here because of its peculiar combination of morphological characters, the likelihood of its being over- looked and redescribed as new because it is not keyed to genus in any present key of North American forms, and the scarcity of information regarding its geographical range. The small elongate lobe on the ninth sternite of the male, fig. 73, is an out- standing character for its separation from Capiiia. The presence of a cross-vein be- yond the tip of the subcosta, which in this instance has real significance, is sufficient to separate it from Leuctra. The short cerci, not exceeding six segments in any of the specimens recorded here, contrasts with the one, modified or unmodified, found in Leuctra, and the many in Capnia. I still consider my assignment of Eucapnopsh to the Leuctridae (1935) as the present best family placement for this genus. New records are as follows: Oregon.—Corvallis, Oak creek: March 31, 1934, E. E. Ball, 3cf, 69; Apr. 1, 1934, R. Dimick, Id', 29; .'\pr. 13, 1934, E. E. Ball, 19. Philomath, Rock creek: March 19, 1933, R. Dimick, 6cf, 109; March 28, 1935, Icf, 29; Greasy creek, Apr. 1, 1936, V. EL. Starr, Icf. King's Vallev, tributarv ot Luckimute river: May 11, 1933, Prentiss & Dimick, 19. Capnia distincta—new species MALE.—Body and appendages brown to black. Wings abbreviated and extending only to base of abdomen. Cerci long, man.\ segmented. Length of body 6.5 mm. No gill remnants visible. Head much wider than pronotum ; later- al ocelli about three times as far apart as from inner margins of compound eyes; median ocellus about as far forward from lateral ocelli as distance between them ; maxillary palpi less than thickness of basal flagellar segments. Pronotum slightly wider than long, with a distinct median line, with indistinct em- bossings. Abdomen with the first four segments normal or without special structures; be- ginning with fifth tergite and extending to ninth with a transverse swollen ridge or hump on each tergite, except that mem- branous cleft of tenth tergite carries for- ward on middle area of ninth and eighth tergites. Supra-anal process, fig. 74, very LATERAL VIEW OF S TERMINAL ABDOMINAL SEGMENTS ? ABDOMINAL STERNITES Fig. 74. — Capnia dislincla. September 1937 PRISON: DESCRIPTIONS OF STONEFLIES 87 luny;, extending about to third segment, divided into two pronglike processes, the upper shorter than the lower and with tip slightly fan shaped, lower prong curving to right of body and tapering to a point. Sub- anal lobes or plates heavily sclerotized, extending up between bases of cerci as two fused plates with outer upper corners slightly hooked and middle prolonged to- wards supra-anal process as a fingerlike projection. Ninth sternite without a lobe at base, posterior margin prolonged and slightl)' recurved upwards to meet subanal lobes. FEMALE.—Simliar in most morphological features to the male. Eighth abdominal sternite, fig. 74, forming a subgenital plate, tip darkly sclerotized, basal portion pale or lightly sclerotized, triangular areas in later- al posterior corners of sternite darkh sclerotized, tip of plate distinctly indented. A broad membranous median stripe extends longitudinally across tergites 1 through 7 and slightly onto the basal part of the eighth. Holotype, male.— Havdeii Valley, Yellow- stone National park, Wyo.: April 4, 1935, H. B, Mills. Allotype, female.—Same data as tor holo- type. Paratypes.—Same data as tor holotype, .?9. Ihis is a very distinctive species. It runs in the ke)' to species of the genus Capnia in iNeedham & Claassen (1925) to the coup- let keying the species iiianitoba Clsn. and c'lliuiihidiia Clsn. It differs markedly from both in the shape of the supra-anal process. Its relationship with columbiana is further indicated in the female by character of the subgenital plate but here too it differs markedl)'. Capnia excavata Claassen Capnia excavata Claassen (192-ta, p. 47). Original description. Among a series of specimens of Capnia sent to me from Oregon I have recognized this species, originally described by Claas- sen on the basis of males from California. In addition to extending the known range for this species, this lot of material has re- xealed what I consider to be the female, hitherto undescribed. S ABDOMINAL STERNITES Fig. 75. Capnia cavata. FEMALE.—Similar in most morphological features to the male. Eighth abdominal sternite, fig. 75, with posterior edge slight- ly projecting backwards in middle portion and evenly sclerotized, a transverse mem- branous band separating seventh and eighth sternites. A broad membranous median stripe extends longitudinally across teigite> 1 up to 9. Allotype, female.— Alsea Mt., Ore.: March 16, 1936, K. Grav. Oregon.—.Alsea Mt.: March 16, K. Gray, 1 cf , 59; March 18, 1936, J. Schuh, 19. Corvallis, Oak creek: Jan. 24, 1934, J. Roaf, 3cf, 29. Fig. 76. Capnia prajecla. Capnia projecta—new species MALE.—Hody and appendages brown. \Vings, (ig. 7b, with membrane mostly light brown, except that portions of cells in middle area of wing are more hyaline, forming spots ; veins dark brown ; venation in essentials typical for genus. Length to tip of wings 7 mm. ; length of body 4.5 mm. No gill remnants evident. Head much wider than pronotum; later- al ocelli about three times as far apart as from inner margin of compound eyes ; median ocellus about as far forward from lateral ocelli as distance between them ; maxillary palpi less than thickness of basal flagellar segments. Pronotum scarcely longer than wide, with a feebly impressed median longitudin- al area or stripe which is about one-sixth as wide as pronotum, some indistinct emboss- ings flanking impressed stripe. ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'ol. 21, Art. 3 Aliddmeii with the first nine segments normal or without special structures except that median area of first few basal tergites is less sclerotized. Tenth tergite cleft ; supra-anal process, fig. 76, recurved back over tergites 9 and 10, slightly enlarged be- fore pointed tip, extending to posterior margin of eighth tergite; eighth and nintli tergites without any special structures or tubercles; in a few specimens median area of ninth tergite is somewhat membranous. Subanal lobes or plates small, somewhat transverse, with median posterior margin produced slightly upward. Ninth sternite without a ventral lobe at base, posterior margin produced and rounded behind. Cerci many segmented. FEMALE.—Similar in most morphological features to the male. Eighth abdominal sternite, fig. 76, with posterior margin in middle produced into a small point ; seventh and eighth sternites otherwise unmodified and separated by membranous area. A broad membranous median stripe extends longitudinally across tergites 1 up to 9. Holotype, male.—Corvallis, Ore., Oak creek: Jan. 24, 1934, J. Roaf. Allotype, female.—Same data as for holo- type. Paratypes. Oregon.—Same data as for holo- type, 1^^,29. Corvallis: Dec. 23, 1933, A. W. Larson, Icf, 149; March 2, 1937, R. E. Rieder, Icf ; roof of agriculture bldg., Jan. 22, 1934, J. Roaf, 2cf; Feb. 4, 1935, R. W. Prentiss, 19; Dixon creek, Ian. 19, 1935, R. W. Prentiss, 3cr, 39, and Jan. 23, 1935, R. W. Prentiss, 29; Oak creek, Jan. 21, 1936, R. W. Prentiss, 19, and Jan. 30, 1935, R. W. Prentiss, 29. .'^Isea, Alsea river: Jan. 5, 1935, R. Dimick, Icf. Lincoln countv, north fork .Alsea river: May 2, 1936, R. E'. Rieder, 19. Philomath, Rock creek: Dec. 2, 1934, R. Dimick, IcT, 39. Benton county, Woods creek: Apr. 11, 1936, R. E. Rieder, 19. In the key to males of the genus Capniti by Needham & Claassen (1925) this species will run closest to gracUaria Clsn. It differs from the latter in having a much shorter supra-anal process, gracUaria hav- ing a supra-anal process which reaches to the seventh tergite, whereas in projecta the supra-anal process extends only to the posterior margin of the eighth tergite. Capnin oenone Neave (1929) is another very closely related species and possibly future studies will show that they are identical, in which case oenone will have priority. According to the drawing of Neave the female of oenone has a subgeni- tal plate which is not produced, whereas in the females of projecta there is an evident medial projection of the posterior margin, fig. 76, of the eighth abdominal sternite. Both sexes of projecta have wings with clear spots in the cells adjacent to the cord, which are not mentioned in the original description or evident in paratypes of oenone sent to me by Neave. Capnia promota — new .species MALE.—Body and appendages brown. Wings in general with membrane rather uniformly light brown, in some specimens darker near veins, area in proximal position d" ABDOMINAL TERGITES 9 ABDOMINAL STERNITES Fig. 77. — Capnia promota. of area beyond costa darkened and usually contrasting with rest of wing membrane; venation in essentials typical for genus, radius where joined by the radial sector somewhat bowed or humped. Length to tips of wings 7-8 mm ; length of body 4-5 mm. No gill remnants evident. Head much wider than pronotum ; later- al ocelli about three times as far apart as from inner margin of compound eyes; median ocellus about as far forward from lateral ocelli as distance between them ; maxillary palpi less than thickness of basal flagellar segments. Pronotum slightly wider than long, with a feebly impressed median longitudinal area or stripe which is about one-sixth as wide as pronotum, some indistinct emboss- ings flanking impressed stripe. Abdomen with the first six segments normal or without special structure; seventh tergite with a somewhat V-shaped SeptciiiluT 1937 PRISON: DESCRIPTIONS OF STONEPLIES 89 membranous area on posterior margin ; eit;hth, ninth and tenth tergites, fig. 77, with median longitudinal membranous area for reception of supra-anal process, this area on eighth tergite more V-shaped and terminating on anterior margin in a small raised ridge. Supra-anal process elongate, slightly enlarged before pointed tip, re- curved back over tergites 8, 9 and 10 and extending about to anterior margin of the eighth. Subanal lobes or plates small, some- what transverse, with median posterior margin slightly produced upwards. Ninth sternite without a ventral lobe at base, posterior margin produced and rounded be- hind. Cerci with manv segments. FEMALE.—Similar in most morphological features to the male. Eighth abdominal sternite, fig. 77, with middle portion of posterior margin produced into a short projection with its middle part slighth pointed ; se\enth and eighth sternites sepa- rated by a membranous area. A broad membranous median stripe extends longi- tudinally across tergites 1 up to 9. Holotype, male.—Corvallis, Ore., roof' of uKficulture bldg.: Jan. 2,?, 1934, K. Gray &: D. Edwards. Allotype, female.—Same data as tor holo- type. Paratypes. Oregon.—Same data as tor holotype, 160^, 469. Same place: Tan. 22, 1934, J. Roaf, 49; Jan. 26, 1935, R. Prentiss, Icf, 189; Jan. 30, 1934, 18cf, 109, 2 mating pairs. Corvallis, Oak creek: Jan. 1, 1936, 3cf, 69; Jan. 15, 1934, Roaf, 1 &, '19; Jan. 16, 1935, R. Dimick, 19, and R. W. Prentiss, 19; Jan. 24, 19,U, Roaf, 19; Jan. 24, 1935, R. \V. Pren- tiss, 10^,49; Jan. 30, 1935, R. \V. Prentiss, 3cr, 49; March 29, 1935, S. Jewett, Jr., 19; .^pr. 2, 1935, J. Schuh, 19. Corvallis: "Jan. 23, 1935, R. W. Prentiss, 19; Jan. 27, 1933, J. Roaf, 19; Ian. 31, 1934, \. P. Larson, Icf ; Feb. 27, 1933, "R. Dimick, 19; March 15, 1935, J. Schuh, 19. Philomath, Rock creek: March 19, 1933, R. Dimick, 159. Wrens, Marv's river: March 16, 1935, R. Dimick, Id', 29;' March 19, 1933, R. Dimick, 39. King's \'alley, tributary of Lucki- mute river: Mav 11, 193.^, Prentiss & Dimick, 19. VVoodburn: Jan. 31, 1935, 1 cT. Stavton, Stavton creek: March 20, 1934, R. Dimick, 19. Hillsboro: March 19, 1936, Schuh & Grav, 2cr,39. This species is very closeh' related to C. t/racilaria Clsn., described from Manitoba. and to C. nenone Xeave, described from Alberta. It is not improbable that large series of specimens from many localities would reveal that the differences at present noted between them break down. The onl\ safe procedure at this time is the recognition of this Oregon material as representing a new species. In the original description of C. gracilaria it is stated that the supra-anal process extends to the seventh tergite and that there is a slight indication of a small median knob on this tergite. This Oregon material does not have a knob on tiie seventh tergite but there is a small raised ridge on the anterior margin of the eightli tergite. It differs, too, from the illustration of the supra-anal process of gracilana as gi\en by Xeedham iSc Claassen (1925) in having the tip more abruptly pointed and in being slightly enlarged before its end. C. (leiione Neave differs in the description of the male by the lack of reference to a raised ridge on anterior margin of the eighth tergite and in the female by the eighth sternite, which is stated to be "not produced." Two paratypic specimens of oenoiie kindly given to me by Neave do not have the ridge on the anterior margin of the eighth tergite visible. It should be noted, too. that the supra-anal process of these paratypes extends only to the posterior margin of the eighth segment, a condition shown in Neave's drawing but contrary to his statement in the original description that this process extends "forward to the posterior margin of the seventh abdominal tergite." If the type and other males of the paratypic series have a supra-anal process extending to the posterior margin of the seventh tergite, this would be another point of difference between oenone and firrjiii'/tii. Dictyopterygella knowltoni — new SI'ECIES MALE.—General color yellowish brown to dark brown. Head, fig. 78, mostly dark brown with some lighter areas, the spot between ocelli and extending back to pro- notum particularly conspicuous. Pro- notum, fig. 78, chiefly dark brown with a medial longitudinal stripe and dark em- bossed markings ; meso- and metathorax mostly black or brownish. Abdomen ap- parently mostly brown, with basal tergites and sternites somewhat lighter. Legs yel- lowish to dark brown. Antennae and cerci light brown. Head wider through compound eyes than width of protonum ; three ocelli form- ing a nearly equilateral triangle, distance between lateral ocelli greatest, lateral ocelli placed on a line slightly back of front mar- gin of compound eyes, somewhat farther 90 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Alt. i ifiiiovecl from one another than from com- pound cjes. Pronotum approximately quadrangular, much broader than long, diameter at front angles apparently greater than at hind angles, front margin bowed, front angles appear sharp, a distinct pattern of raised rugosities on surface each side of median stripe. Legs with first tarsal segment mucii longer than second and third together, the second much shorter than third. Fig. 78. — Diclyoplerygella knowltoni. Wings, fig. 78, with venation as in illustration, tip of wing with branches of radial sector somewhat turned upwards. Wing membrane stained with brown and veins dark brown. Hind wing with eight branches of anal veins reaching margin of wing. Abdomen, fig. 78, with tergites normal except for small areas on terminal segments which are heavily covered with spinulae ; tenth tergite not cleft for reception of the supra-anal process. Ninth sternite not pro- duced and recurved upwards, without a disklike pad. Subanal hook very peculiar, prolonged backwards as a projection from bodv, the two plates together when viewed from above or below forming a mushroom- shaped structure. Length to tip of wings, 15 mm.; lengtli to tip of abdomen, 12 mm. No gill rem- nants found on any body area. Holotype, male.—Loyun, Ut;ih: luiic 23, 1929, G. F. Knowlton. " I his new species is unique among North American stoneflies described to date b\' virtue of the peculiarly prolonged subanal plates, fig. 78. Tentatively, pending the collection of fresh material and the female, it is placed in the genus Dictyopteryyellu Klapalek (1904). This genus is character- ized among other things by the peculiar subanal plate which in such a European species as D. uaiiseni Kempny is very sug- gestive of knrju'ltoiii as here described. Dictyopterygella is placed by Klapalek in the Perlodidae. According to the author's studies the Perlodidae of North America (Ferlndes, Isogenus and Hydru- pcrla) all have peculiar fingerlike gills on the submentum of the nymphs and rem- nants of such gills in the adults. I cannot find such remnant submental gills on the submentum of knowltoni but it must be said that the type was originally a pinned specimen and it is possible that either such gills cannot now be located in the relaxed specimen, have been accidentally lost through handling or never were present. My judgment is that they never existed and accordingly I am skeptical regarding the placem.ent of this new species in Perlodidae. As far as I am aware the species previously assigned to Dictyopterygella are rarities, have never been studied with reference to the presence of remnant submental gills or have never been associated with their nymphs. It will not be surprising, there- fore, if knoii'honi and the genus to which it belongs will eventually be placed in the group of genera now going by the family name of Perlidae in North American liter- ature. The type of wing venation is not sufficient to place the genus as to family. I take pleasure in naming this species for its collector. Dr. G. F. Knowlton, who has sent to me for studv many specimens of Plecoptera from Utah. Hydroperla parallela Prison Jlydroperla parallela I'Vison (1936, p. 261). Original description. The original description of this species was based upon a single male (Frison 1936). Since then additional specimens of the male have been received, and also the undescribed female, a brief description of which is here presented. FEMALE.—Similar in most morphological respects to the male (Frison 1936). Color Sciiti'iiilK-r l'',?7 PRISON: DESCRIPTIONS OP STONEFLIES 91 ));itti.'iii of dorsum of head and pronotum as in rig. 79. Subgenital plate, fig. 79, well developed but only slightly extending over ninth sternite, posterior margin essential!) straight witii corners angulate. Allotype, female.— Cultus lake, B. C, Sweltzer creek: Apr. 28, 1935, W. E. Ricker. (J HEAD AND PRONOTUM Fig. T).— Uy,iroperl,i parallela. Other records for this species which ha\ c accumulated since it was originalh de scribed are as follows: British Coi.imbia.— Cultus lake: Apr. 18, l')36, W. K. Ricker, 19; Apr. 21, 1936, \V. K. Ricker, IcT. Oregon.— Clatskanie, Beaver creek: May 9, 1936, J. .Schuli, IcT. Hillsboro: March 19, 1936, Gray & Schuh, Icf. Chloroperla orpha — new species MALE.— [dominant color a pale greenisli white in life and pale yellowish white when preserved. Dark or black areas are as fol- low s: ocelli and compound eyes, fig. 80, hiteral margins of pronotum, and a narrow longitudinal stripe extending across ab- dominal tergites as in fig. 80. Cerci and antennae at base concolorous with bod> , segments of antennae beginning a short distance from base progressively becoming darker to black. \Vings with membrane and veins pale. Head wider through compound e}es than width of pronotum ; three ocelli form- ing a nearly equilateral triangle, lateral ocelli placed about on a line with posterior margin of compound eyes, about twice as far apart as each lateral ocellus is distant from compound eye. Antennae many seg- mented, basal segments not much longer than broad, middle and apical segments about of equal length and much longer than broad. Pronotum slightly broader than long angles rounded, pronotal flange not well developed, embossings not evident. Legs slender ; first and second tarsal seg- ments very short, third tarsal segment over twice as long as length of iirst and second togetiier. Wings extending well beyond tip of abdomen ; witli membrane and veins pale ; no anal lobe on hind wing and in this im- poitant respect, as well as venation in general, agreeing with Chloroperlii as now recognized for North America. Dorsal segments of abdomen without special structures. Tenth tergite somewhat cleft for reception of a small tablike supra- anal process. Subanal lobes not specialized. Ninth sternite produced and turned up- waxA over tenth segment so that it is not \ isible from below, without a padlike disk near middle of apical portion. Length to tip of wings 7 mm. ; length t(j tip of abdomen 5.5 mm. No gill rem- nants on any body area. FEMALE.—Not known. Holotype, male.—Xamakagon river, Spoon- er, Wis.: June ,S, 1936, Prison & Ross. Paratypes. -Same data as for holotype, 11 cf . This species is of special interest because the genus was considered by Needham & Claassen (1925) to contain but a single North American species and all my ma- terial, previous to the collecting of these specimens, has supported this view. The lack of an anal lobe on the hind wing sepa- rates this small delicate species frcjm other nd tip of abdomen ; membrane but slighth tinged with brown, veins dark brown and con- trasting; venation slightly variable in right or left wings or between individuals but essentially typical for the genus as no«- recognized in North America. Abdomen with dorsal segments without special structures. Tenth tergite nut cleft : subanal lobes modified into a pair of up turned or recurved pointed hooks which are about as wide at base as diameter of basal segments of cerci. Ninth sternite strongly produced and turned upward around tenth segment so that it is not visible from below, without a distinct padlike disk near middle of apical portion. Eighth sternite with a small lobe, wider than long, in middle of posterior margin. Length to tip of wings 14 mm.; length to tip 'niph. Allotype, male.—Same data as for holotype. Paratypes. Indiana.—Knox, Yellow river: May 24, 1937, H. H. Ross, 21 cT, 49. Michigan.—Omer, Rifle river; May 21, 1936, Prison Se Ross, IcT. Big Rapids, Muske- gon river: May 22, 1936, Prison & Ross, Icf, 89. Grayling, Klanistee river: June 17, 1935, T. H. Prison, 4rf', 49. Lovells, Au Sable river: May 22, 1935, Id; north branch, May 24, 1936, J. W. Leonard, Icf. Crawtord county, north branch Au Sable river: June 16, 1935, J. \V. Leonard, 2d", 39. Cheboygan county. Pigeon River State Porest, Pigeon river: July 21, 1935, J. \V. Leonard, 6cf, night at light. Otsego county, Pigeon river: June 23, 1936, J. W. Leonard, 19. Wisconsin.—Same data as tor holotype, 39; same data except not reared, IScT, 89. The adults of this species are best dis- tinguished from other species of this genus by the characteristic dark patch on head near ocelli and in the female by the truncate subgenital plate which sticks out from the h()d\- at an angle, hg. 83. In all respects this is a typical species of Isoperln (r. s. ) , as now recognized in North America, be- longing to the group of species now having /. hilnieata (Say) as type. ihe nymph of this species has been col lected as well as the adult and therefore its description is given. Association of the nymph with this new species is based upon reared specimens. The nymph is quite characteristic of other Isoperla (r. s. ) as this genus is now recognized in North America. It is perhaps most easily sepa- rated from other species known to me by the two longitudinal rows of prominent spots on dorsum of thorax. NYMPH.—General color of head, thorax and abdomen a whitish yellow with dark markings as in fig. 84. The most important dorsal dark markings are the broad trans- verse band across head, the two longitudi- nal rows of spots on thorax, and the three narrow longitudinal stripes on abdomen. Cerci pale \ellowish brown. Head with three ocelli forming a nearh equilateral triangle, lateral and median ocelli occupying the same relative position as in adult. No occipital ridge. Labium and maxillae as in lig. 83. Pronotum about twice as wide as long, all angles well rounded ; fringed with short as well as some long hairs ; marginal groove well defined on anterior and posterior mar- gins but absent on lateral margins. Meso- notum with wing pads extending almost straight backwards, those on metanotum extending slightly outward. Legs very little flattened ; hind margins of femora, tibiae and tarsi with a fringe of long fine setae. Tarsal segments 1 and 2 very short; third segment long, about three times as long as first and second combined. Cerci many segmented, moderately long, stout at base, segments progressively longer apically, distal half with a row of long fine setae on dorsal surface in addition to shorter ones encircling segments. Approximately mature specimens with a body length, exclusive of appendages, of about 10 mm. Submental, thoracic and abdominal gills entirely lacking. Nymphs. Michigan.—Omer, Rifle river: May 21, 1936, Prison & Ross. Grayling, Manis- tee river: May 22, 1936, Prison & Ross. Mio, Fig. 84.—Nymph of Isoperln in 96 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \'ol. 21, Art. 3 All Sable river; May 21, 19J6, Krison & Ross. Lovells, All Sable river: May 22, 1936, Prison & Ross. Hale, Au Gres river. May 21, 1936, Prison & Ross. Wisconsin.— Dells, Wisconsin river: June 5, 1936, Prison & Ross. Spooner, Namakagon river: June 5-6, 1936, F'rison & Ross. Cast nymphal skins. Michigan.—Honor, Platte river: Sept. 16, 1936, Ross & Burks. Wisconsin.—Spooner, Namakagon river: June 5-6, 1936, Prison & Ross. AUoperla exquisita Frison Alloperla exquisita Prison (1935b, p. 337). This species was originally described from males only and from material collect- ed in Oregon. Additional material from Washington and British Columbia has ABDOMINAL STERNITES Fig. %'a.^Alloperla sqnisila. made available the previously unknown female and therefore the description of this sex is now given. FEMALE.—Similar in most morphological features to the male (Frison 1935b). Eighth abdominal sternite, fig. 85, with >ubgenital plate produced backwards over about one-half of ninth sternite and with posterior margin approximately truncate. Allotype, female.—Shucksan, Wash., Bagley creek, 2700 feet elevation; July 24, 1936, H. H. Ross. British Columbia.—Cultus lake, Smith Palls creek: May 20, 1935, W. E. Ricker, Icf, 19. Washington. — Shucksan, Bagley creek, 2700 feet elevation: July 24, 1936, H. H. Ross, 5cf , 119; Razorhone creek, 3200 feet elevation: July 24, 1936, H. H. Ross, Hd', 119. AUoperla occidens—new species MALE.—Body, cerci, antennae and legs in general a pale yellowish white. Dark or black areas are as follows: ocelli and com- pound eyes, fig. 86, lateral margins of pro- notum, a U-shaped mark on meso- and metanotum, a broad median longitudinal stripe extending across all abdominal ter- gites up to the ninth, and basal segments 1 through 3 with a small dark stripe on each lateral margin running parallel to median stripe. Head wider through compound eyes than width of pronotum ; median ocellus located about in line with anterior margins of compound eyes, lateral ocelli located well anterior to line connecting posterior margins of compound eyes, distance be- tween lateral ocelli greater than distance between a lateral ocellus and adjacent compound eye. Pronotum much wider than long, front angles rather sharp, hind angles more rounded. Dorsum of abdomen as in fig. 86. Supra- anal process small, inset on tenth tergite, forming a fingerlike projection which in lateral view is slightly swollen at tip ; eighth and ninth tergites without raised ridges. Tenth tergite cleft for reception of supra-anal process, without distinct inward- pointing lobes or hooks at bases of cerci. Wings extending well beyond tip of abdomen ; with membrane and veins pale ; a well-formed anal lobe on hind wing and in this respect, as well as venation in gener- al, agreeing with Alloperla as now recog- nized in North America. Length to apex of wings 8 mm. ; length to tip of abdomen 6 mm. No gill remnants on any bodv area. (? ABDOMINAL SEGMENTS d" ABDOMINAL TERGITES Fig. ?t(i.- Alloperla ncciilens. Septciiilicr ]'>M PRISON: DESCRIPTIONS OF STONEFLIES 97 FEMALE.—Similar in most morphological characters to the male. Median longitudi- nal dark stripe on abdominal tergites ex- lending only to eighth tergite, and lateral stripes only on first and second tergites. f^ighth abdominal sternite, fig. 86, with subgenital plate extending in middle area over about one-half of ninth sternite, posterior margin somewhat broadly tri- angular and depressed. Holotype, male.—Shucksan, Wash., Razor- hone creek: July 24, 1936, H. H. Ross. Allotype, female.—Same data as for holo- type. Paratypes.—Same data as for holotvpe, Icf, 49. This species resembles ./. exqu'niUi Prison (1935b) in general color pattern. It differs in the male, however, in lacking a trans\erse ridge on ninth tergite and in the female the subgenital plate is more triangular. as defined by Xeedham iS: Claasscn. The name fiiiiins/i must therefore be pl.iced in s\non\niv. SYNONYMY Acroneuria lycorias (Newman) Acroneuria cueslae Ricker (19351), p. 260) »New synonymy (cf, 9). A male and a female paratype of Acro- neuria cuesiae Ricker, kindly sent to me for the Survey collection by \V. E. Ricker, prove upon close study and comparisons with other material to be the species ./. Ixcur'ias as defined b\' Needham li: Claassen ( 1925). The name cuestae. therefore, must be relegated to synonymy. m Togoperla"media' (Walker) P Acrotieuria salvelini Ricker (193.Sli, p. 261). New synonymy (91. A stud}' of a paratypic female sent to me for the SURVEY collection by W. E. Ricker and a second paratypic female loaned by the Canadian National Museum prove that these are the same as the common northern and eastern American species now going by the name of tnedin (W-Aktr). The name salvelini, therefore, must be synonymized. Togoperla immarginata (Say) Acroneuria fiimosa Ricker (193.ili, p. 262). New synonymy (9). Examination of a paratypic female of A. funiosa Ricker, loaned by the Canadian National Museum, and comparisons with other material, including a female specimen and a nymphal skin named as jumosa by Ricker and sent to me by him, have enabled me to recognize this as immarginata (Say) BIBLIOGRAPHY Banks, Nathan 1895 New neuropteroid insects. Irans. Am. Ent. Soc. 22:313-16. 1905 New genera and species of Perlidae. Psyche 12:55-7. June-Aug. 1906 On the perlid genus Chloroperla. Ent. News 17(5"l:174-5. May. Claassen, Peter W. 1923 New species of North American Ple- coptera. Can. Ent. 55(12): 281-92. 1 pi. Dec. 1924a New species of North .•\merican Capniidae (Plecoptera). Can. Ent. 56(2):43-8. Feb. 1924li New species ot North American Capniidae f Plecopteral. Can. Ent. 56(31:54-7. March. Prison, Theodore H. 1935a The Stoneflies, or Plecoptera, of Illi- nois. III. N.'Vt. Hist. Sirv. Bil. 20(4):281^71. Frontis-l-344 f^gs., bibliog., index. 1935b New North .American species of the genus .Alloperla. Trans. \m. Ent. Soc. 61:331-44. 1936 Some new species ot stoneflies from Oregon (Plecopteral. .Ann. Ent. Sue.'.Am. 291 2 1:256-65. June. Hagen, Hermann 1861 Synopsis of the Neuroptera of North .America. Smiths. Misc. Coll. xx-|- 347 pp. Smithsonian Institution, Washington, D. C. July. Kimmins, D. £. 1936 Synonymic notes on the genera Chloroperla, Isopteryx and Isoperla I Plecoptera). Jour. Soc. Br. Ent. 2:121-4. March. Kalpalek, Fr. 1904 Europske druhy celede Dictyoptery- gidae. Rozpr. Ces. Akad. 13fl7):5. 1909 Revision der gattung .Acroneuria Pict. Bui. I lit. Acad. Sci. Emp. Franz Jos. 1, 14:234-47. Nov. Neave, Ferris 1929 Reports of the Jasper Park lakes investigations 1925-26, II. Ple- coptera. Cont. Can. Biol. &: Fish. 4 [n. s.] (13):159-68. 2 pis. 1934 Stoneflies from the Purcell range, B.C. Can. Ent. 66(l):l-6. 2 pis. Jan. Needham, J. G. and P. W. Claassen 1925 Monograph of the Plecoptera or Stoneflies of .America North of Mexico. Thomas Sav Found. Pub. 2. 397 pp., 50 pis. 98 ILLINOIS NATURAL HISTORY SURVEY BULLETIN \\i\. 21, Alt. .? Okamoto, H. 1922 Zweiter beitrag zur kciuiiiss dcr japanischen Plcciiintra. Bill. Ay. Kxp. Sta. Gov. Gen. Chosen, Suigen. 1:1-46. 6 pis. Ricker, William E. l').1,S;i Descriptions of three new Canadian perlids. Can. Knt. 67(9) •.1<;7-2()1 . .Sept. IQ.^Sb New Canadian periids (part II). Can. Knt. 67(12) :256-64. 1 pi. Dec. Walsh, Benjamin D. 186.^ Perlina. Proc. Knt. Soc. I'hila. 2(.^):186-8. Oct. INDEX abnormis, Acroneuria, 81 Acroneuria, 81 abnormis, 81 arida, 79 cuestae, 97 evoluta, 79 fumosa, 97 internata, 81 lycorias, 97 pennsylvanica, 81 perplexa, 79 salvelini, 97 sp. a, 79 aequalis group, 61 aequalis, Sialis, 58, 61, 63, 66, 77 Alloperla, 92, 96 exquisita, 96, 97 occidens, 96 americana group, 61 americana, Protosialis, 70, 71 Semblis, 60, 61, 70, 71 Sialis, 57, 59, 61, 63, 70, 71 arida, Acroneuria, 79 a.'valis, Sialis, 61, 63,68 bilineata, Isoperla, 95 biology, 57-59 brevicauda, Capnia, 85 Eucapnopsis, 85 brevis, Chloroperla, 92 calcarea, Hastoperla, 92 californica group, 61, 69, 70 californica, Sialis, 58, [59, 61. 63, 66, 68, 69 Capnia, 86, 87, 88 brevicauda, 85 Columbiana, 87 distincta, 86 excavata, 87 gracilaria, 88, 89 manitoba, 87 oenone, 88, 89 projecta, 87, 88 promota, 88 vernalis, 78 Chauliodes, 59 Chloroperla, 91, 92 brevis, 92 cydippe, 92 idei, 92 milnei, 92 orpha, 91 tripunctata, 92 Columbiana, Capnia, 87 concava, Sialis, 61, 63, 73 cornuta, Sialis, 61, 63, 66, 69 Corydalidae, 59 Corydalinae, 59 Corydalis, 59 crosbyi, Hydroperia, 82, 83 cuestae, Acroneuria, 97 cydippe, Chloroperla, 92 Dictyopterygella, 90 knowltoni, 89 nanseni, 90 distincta, Capnia, 86 Eucapnopsis, 86 brevicauda, 85 evoluta, Acroneuria, 79 excavata, Capnia, 87 exquisita, Alloperla, 96, 97 ferrugineus, Sialis, 70, 71 forcipata, Leuctra, 85 fuliginosa, Sialis, 68, 69 fumosa, Acroneuria, 97 genitalia, terminology, 59 glabella, Sialis, 61, 63,71 gracilaria, Capnia, 88, 89 habitat preference, 57 hamata, Sialis, 58, 61, 63, 66, 70 harti, Hydroperia, 82, 83 hasta, Sialis, 61, 63, 74 Hastoperla, 92 calcarea, 92 holders of material, 60, 79 Hydroperia, 83, 90 crosbyi, 82, 83 harti, 82, 83 parallela, 90 varians, 78, 82 Hymenoptera, 59 idei, Chloroperla, 92 immarginata, Togoperia, 97 intumata group, 61, 73 infumata, Sialis, 57, 61, 63,66, 68, 73, 74 internata, Acroneuria, 81 iola, Sialis, 58, 61, 63, 66, 68 Isogenus, 90 Isoperla, 92, 93, 95 bilineata, 95 pinta, 92 truncata, 94 Isopteryx, 92 itasca, Siabs, 57,58, 61,63,66, 71, 72, 73 joppa, Sialis, 58, 61, 63, 66, 67, 68, 69, 70 K kansensis, Peria, 82 Togoperia, 82 knowltoni, Dictvoptervgella, 89 Leuctra, 86 forcipata, 85 occidentalis, 85 purcellana, 85 Leuctridae, 81 lutaria, Semblis, 60, 61 lycorias, Acroneuria, 97 M manitoba, Capnia, 87 material, present holders, 60, 79 Mecoptera, 59 media, Togoperia, 82, 97 Megaloptera, 57, 59 milnei, Chloroperla, 92 mohri, Sialis, 57, 58, 59, 61,63, 74 morrisoni, Sialis, 76 nanseni, Dictyopterygella, 90 Nemoura, 85 oregonensis, 83 Septcnihcr I ''J/ 99 N (concl.) lul.crciiliit.i, 84 McvMck-nsis, Si:ilis, 57, (,] , 6,^, 76 Nciiroptcra, 59 imldciis, Allopcria, 96 Sialis, 5S, ()1, 63, 60, 69 rpciidentalis, Leuctra, 85 iienone, Capnia, 88, 89 oregonensis, Nemoura, 83 orpha, Chloroperla, 91 parallela, Hyilroperla, 90 pennsylvanica, Acroneuria, 81 Perla kansensis, 82 varians, 82 Perlodes, 90 Perlodidae, 90 perplexa, Acroneuria, 79 phalaenoides, Semblis, 61 Phryganeidae, 61 pinta, Isoperla, 92 Plecoptera, 78 projecta, Capnia, 87, 88 promota, Capnia, 88 Protosialis, 60, 61 amencana, 70, 71 purcellana, Leuctra, 85 nitunda, Sialis, 5S, 61, 6.?, 75 salvelini, Acroneuria, 07 Semblis, 60, 61 americana, 60, 61, 70, 71 lutaria, 60, 61 phalaenoides, 61 segregation ot species, 58-59 Sialidae, 57, 59, 60 Sialinae, 59 Sialis, 57, 59, 60, 61 aequalis, 58, 61, 63, 66, 77 americana, 57, 59, 61, 63, 70, 71 arvalis, 61, 63, 68 californica, 58, 59, 61, 63, 66, 68, 69 concava, 61, 63, 73 cornuta, 61, 63, 66, 69 terrugineus, 70, 71 fuliginosa, 58, 69 glabella, 61, 63, 71 hamata, 58, 61, 63, 66, 70 hasta, 61, 63, 74 infumata, 57, 61, 63, 66, 68, 73, 74 iola, 58, 61, 63, 66,68 itasca, 57, 58, 61, 63, 66, 71, 72, 73 ioppa, 58, 61, 63, 66, 67, 68, 69, 70 inoliri, 57, 58, 59, (,|, 63, 74 niorrisoni, 76 ncvadensis, 57, 61, 63, 76 occidens, 58, 61, 63, 6(>, 69 rotunda, 58, 61, 63, 75 vagans, 58, 61, 63, 66, 75, 76, 77 velata, 57, 58, 59, 61, 63, 66, 71, 73 sp. a, Acroneuria, 79 Togoperla, 82 succession, seasonal, 57 Togoperla, 82 immarginata, 97 kansensis, 82 media, 82, 97 sp. a, 82 tripunctata, Chloroperla, 92 truncata, Isoperla, 94 tuberculata, Nemoura, 84 vagans, Sialis, 58, 61, 63, 66, 75,76, 77 varians, Hydroperla, 78, 82 Perla, 82 velata, Sialis, 57, 58, 59, 61, 63, 66, 71, 73 vernalis, Capnia, 78