Echinogammarus 489^ 



about '/g longer than body, 1^* Joint stout, 3'^ not veiy short, flagellum about 

 5 times as long as peduncle, joints reaching 200 in number, accessory 

 flagellum 14 — 17-jointed. Antenna 2 about ^s length of antenna 1. ultimate 

 Joint of peduncle longer than peuultimate, flagellum rather longer than 

 peduncle, 20 — 42-jointed. Gnathopods 1 and 2 nearly equally long, gnatho- 

 pod 1 with 6*^» Joint piriform, gnathopod 2, 6**^ Joint narrowly oblong, with 

 Short transverse palm in 9. smaller than 6 '^'^ Joint of gnathopod 1, but in ö 

 widening to the oblique palm, and both broader and longer than 6^^ Joint 

 of gnathopod 1. Peraeopods 3 — 5, 2'^ Joint moderately broad, bind margin 

 slightly convex or sinuous, or nearly straight, euding below with a projecting 

 acute angle. Uropods 1 and 2 reaching end of shorter ramus of uropod 3. 

 üropod 3, inner ramus -/.^ — ^/^ as long as outer, plumose setae on both 

 margins; outer ramus having them only on its inner margin; its 2^ Joint 

 distinct. Colour reddish yellow. L. 34 mm. — l'ar. nbyssomm is distinguished 

 by longer extremities, slender 6*^ Joint to gnathopods 1 and 2, longer uropod 3, 

 with relatively shorter inner ramus, colour bright rose-red or reddish yellow, 

 eyes whitish (becoming dark in spirit) or reddish. and plumose setae on 

 outer margin of outer ramus of uropod 3. L. 41 mm. 



Lake Baikal. Deptli 150-1000 in. 



18. E. stenophthalmus (Dyb.) 1874 Ganuitanis s., B. Dybowsky in: Horae 

 Soc. ent, Ross., r. 10 siippl. p. 90 | 1899 Echinogantniarus s., T. Stebbing in: Tr. Linn. 

 Soc. London, ser. 2 r. 7 p. 429 ; 1893 Gammarus fluvüifilis (part.)?, A. Della Yalle in: 

 F. Fl. Neapel, k. 20 p. 930. 



Peraeon segment 7 and pleou segmeuts 1 — 6 with dorsal spiues on 

 slight ridge-like elevations of the bind margiu; on peraeon segment 7 only 

 2 middle rows, on all the pleou segmeuts 2 middle and 2 lateral, on segments 

 2 and 3 the spines more numerous than on the others, so as to form a 

 continuous row; spines in a group 4 — 6, rarely 1-3. Eyes naiTowly to 

 linear reniform, scarcely widened below, 4 times as deep as broad. Antenna 1 

 as long as body, thrice as long as antenna 2, 1^* Joint thick, almost as long as 

 ultimate Joint of peduncle of antenna 2, flagellum more than 4 times as long as 

 peduncle, 1 2 1 -joiuted, accessory flagellum 8-joiuted. Antenna 2. flagellum shorter 

 than peduncle, 23-joiuted. Gnathopod l,6*'^jointsleuderly piriform. Gnathopod 2, 

 6^1^ Joint oblong. Peraeopods 3—5, 2^ Joint rather broad, with convex front 

 and bind margin, the latter ending below in an acute angle. Uropods 1 and 2 

 reaching about the middle of uropod 3. üropod 3, outer ramus without 

 plumose setae on outer margin. inner -/g as long, with plumose setae on 

 both margins. L. over 30 mm. 



Luke Baikal. Depth 200 m. 



19. E. schamanensis (Dyb.) 1874 Gammarus s:' B. Dybowsky in: Horae 

 Soc. ent. Ross., «.10 suppl. p. 91 | 1899 Echinogammarus s., T. Stebbing in: Tr. Linn. 

 Soc. London, ser. 2 v.7 p. 429 | 1893 Gammarus calcaratus (part.)?, A. Della Valle in: 

 F. Fl. Neapel, v. 20 p. 930. 



Peraeon segment 7 and pleon segments 1 — 6 with dorsal spines, in 

 regulär and usually separate groups in 1 cross-row on each bind margin; 

 peraeon segment 7 with 2 middle groups, all the rest with 2 lateral and 2 middle 

 groups, the latter coalescent on pleon segments 4—6, spines 2 — 6 in middle 

 groups, 3 — 6 in lateral groups. Eyes large and broad, reniform, black. Antenna 1 

 almost as long as body, peduncle thicker and only a little shorter than that 

 of antenna 2, 3*^ Joint relatively longer than in nearly related species, flagellum 



