490 Echinogammarus 



twice as long as peduncle, 75 — 84-jomted, accessory flagellum 7- or 8-jointed. 

 Aütenna 2 about ^/^ as long as antenna 1, flagellum shorter than peduncle, 

 26 — 35-jointed. Gnathopod 1, 6*^ Joint broad, piriförm, gnathopod 2, 6*^1 Joint 

 oblong. Peraeopods 3 — 5, 2^ Joint about ^s longer than broad, bind margin 

 sinuous, acute lower corner not prolonged into a tooth. üropods 1 and 2 reaching 

 about % of uropod 3. Uropod 3, outer ramus without plumose setae on outer 

 margin, inner ramus % as long as outer. Colour reddisb yellow. L. about 23 mm. 



Lake Baikal. Depth 200 m. 



20. E. leptoeerus (Dj'b.) 1874 Gammarus l. + Gr. l var. nematöcerus, B. Dybowsky 

 in: Horae 8oc. ent. Boss., v. 10 suppl. p. 85 t. 8 f. 2 ; p. 85 t. 8 f. 3 \ 1899 Echinogammarus l., 

 T. Stebbiug in: Tr. Linn. Soc. London, ser. 2 v.l p. 429 | 1893 Gammarus ßuviatilis 

 (part.)?, A. Delia Valle in: F. Fl. Neapel, u 20 p. 929. 



Pleon Segments 1 — 3 with about 18 dorsal spiues in 3 or 4 little 

 groups or in a coutinuous row on bind margin of each; Segments 4 — 6 with 

 7 — 9 spines in 3 groups. Eyes large aud broad, irregularly reuiform, bind 

 margin uneven and lobed, black. Antenna 1 a little longer than body, nearly 

 thrice as long as antenna 2, 1^* Joint stout, as long as 2*^ and 3*^ combined, 

 flagellum about 6 times as long as peduncle, 43 — 9ü-jointed. accessory flagellum 

 4 — 7-joiiited. Antenna 2, ultimate Joint of peduncle slender, longer than 

 peuultimate, flagellum a little shorter than peduncle, 11— 18-jointed. Gnathopods 

 1 and 2, 6**^ Joint rather large, in gnathopod 1 piriförm, in gnathopod 2 

 oblong, in ö widening to the palm. Peraeopods 3 — 5, 2*^ Joint slender, 

 lower hiud angle unimportant. Uropod 1 reaching middle of uropod 3. 

 Uropod 3, inner ramus only a little shorter than outer, both with plumose 

 setae on their margins. Colour reddish yellow. L. 14—1 5 mm. — Vor. nematöcerus 

 is distinguished by more slender build of body, longer and more slender 

 legs, flagellum of antenna 2 longer than peduncle, eyes more narrowed above, 

 more uumerous setae on uropod 3, aud whitish colour. L. 22 — 23 mm. 



•Lake Baikal. Depth 150—670 m. 



2'1. E. toxophthalmus (Dyb.) 1874 Gammarus t., B. Dybowsky in: Horae 

 Soc. ent. Boss.. i\ 10 suppl. p. 77 | 1899 Echinogammarus t., T. Stebbing in: Tr. Linn. 

 Soc. London, ser. 2 v.l p. 4"J9 | 1893 Gammarus flrwiatilis (part.)?, A. Della Valle in: 

 F. FI. Neapel, u 20 p. 931. 



Pleon Segments 1 — 6 with dorsal spiues in a Single cross-row of 

 regulär groups on low elevations of each segmenfs bind margin, 1 — 3 spines 

 in each of the 2 middle groups, 4 — 8 in the 2 lateral groups, except on 

 Segment 6 where the number is reduced to 2. Eyes long, reniform, much 

 curved, widened below, not widely separated above, black. Antenna 1 about 

 % as long as body, little longer than antenna 2; 1^* Joint stout, considerably 

 shorter than ultimate Joint of peduncle of antenna 2, flagellum about 2^/^ 

 times as long as peduncle, 45-jointed, accessory flagellum 5-joiuted. 

 Antenna 2, flagellum a little shorter than peduncle, 26-jointed. Gnatho- 

 pods 1 and 2, 6*^^^ Joint slender, in gnathopod 1 piriförm, in gnathopod 2 

 oblong. Peraeopods 3 — 5, 2* joint moderately broad, bind margin almost 

 straight, ending below in a shortly projecting angle. Uropod 1 reaching 

 nearly the end of uropod 3. Uropod 3, inner ramus about ^^ shorter than 

 outer, both with plumose setae on both margins. Colour clear violet. 

 L. 20 mm. 



Lake Baikal. Depth 120 m. 



