HIRUDINEA AND OLIGOCH.ETA OF THK GREAT LAKES REGION. 167 



Slavina gracilis (Leidy) Vejdoveky. 

 Kais riraciUa Leidy, Journal Academy of Natural Sciences of Phila., ser. 2, vol. ii, 18S0. p. -13. 



The few examples by which this species is represented in the collection are in very poor condition 

 and much distorted and obscured by the mucous tubes in which they are enveloped, and which have 

 been hardened and much shrunken by the alcohol. There can be no doubt that they belong to Leiily's 

 species, but the distinction of this from ,S'. appendiculata ( Udeken) Vejdovsky is not so clear. Sensory 

 papilhe are well developed and on each somite are arranged in a circle of large ones in the set* zone, 

 and another of alternating smaller ones, both provided with sensory hairs; the anus is surrounded by 

 4 or 6 papillfe. 



Birgeboro, August 19, 1893, 1 specimen; Lake St. Clair, unlabeled vial, 1 specimen; and Round 

 Lake, July 16, 1894, 2 specimens, with A7((s. 



Dero limosa Leidy. 



Da-o Umom Leidy, American Naturalist, vol. xiv, 18S0, p. ■1'22. 



This well-known naid appears to be abundant throughout the entire region covered by these 

 collections. The position of the budding zone is very variable, being found as far forward as XX in 

 small, and as far back as XXXVIII in large individuals, while the total number of segments varies 

 from 36 to 76 in gemmating examples. 



New Baltimore, Mich., August 19, 1893, abundant among algcc; Lake St. Clair, unlabeled bottle, 

 numerous; Lemna Pond, South Bass Island, Ohio (18n and 78((), July 7-15, 1899, plentiful; swamp 

 near East Point, Ba.»s Island (117), August 27, 1898, numerous; Sandusky, Ohio, West Harbor (207a), 

 2 specimens; Squaw Bay, Put-in Bay Island, Ohio (36a), 1 specimen among bryozoans, July 12, 1899. 



Stylaria lacustris (Linnicus) Lsmarck. 

 ■'itylaria laeusiris, Vejdovsky, System u. Morphologie der Oligochieten, p. 30, ls84. 



This also is an abundant species, particularly in the Lake St. Clair region, but in Lake Erie 

 appears to be less plentiful than the next. Among the material from station 17 in Carp Lake is one 

 sexually mature example with well-marked clitellum and genital seta;. Most of the specimens, how- 

 ever, bear buds in various stages of development. Although the resendslance of our specimens to 

 descriptions based on European examples is remarkably close, the ventral set» are constantly more 

 strongly hooked than Vejdovsky's figures indicate, and there are other slight differences. 



Stylaria liieiistris was taken at the following stations in and about Lake St. Clair. Birgeboro, 

 August 19, 1893, about 15 specimens with Cluttoyasler diaphaims; New Baltimore, August 24, 1893, with 

 other naids common among algie in bottom tow (Professor Ward furnishes some excellent drawings of 

 sijecimens from this lot); Fox Lake, a large number; also taken in the Birge bottom tow net at 

 Crooked Lake (stations 3 and 5), Burt Lake (9), Mullet Lake (11 and 13), Carp Lake (17 and 18), and 

 Bear Lake (20). Lake Erie localities are Put-in Bay (37a and 38a), July 10, 1899, bottom tow, plen- 

 tiful; East Harbor, Sandusky ( 182a), August 4, 1899, several with S. fosm'laris; Sandusky, Ohio (212a), 

 August 8, 1899, two specimens; Erie, Pa., boat landing, August 16, 1899, numerous; same date and 

 locality (315a and 316a}, several, with a large number of X. fo.v.sa/aris. 



Stylaria fossularis Leidy. 



Stylaria fossularis Leidy. Proceedings Academy of Natural Sciences of Philadelphia, vol. v, 1852. p. 287. 



Although students of the Oligochseta have generally failed to discriminate between this species 

 and S. lacnstriK, the two are in reality perfectly distinct and are easily separated, as was done by Leidy, 

 by the form of the prostomium (fig. 3), which in this species is prolonged medially into the base of 

 the proboscis and lacks altogether the lateral lobes which are so conspicuous in .S'. lacustris. The Lake 

 Erie material is beautifully preserved and permits a detailed study of the specimens, which correspond 

 exactly with those occurring in the neighborhood of Philadelphia. In the preserved state the brain 

 is 2J times as wide as long, v.-ith a nearly straight anterior margin and a pair of prominent poste- 

 rior lobes separated by a deep median emargination. Almost all of the specimens are in process of 



