488 Echinogammarus 



and delicate. Gnathopods 1 and 2, 6*^ Joint not large, piiiform (in figure of 

 gnatliopod 2, G*** Joint oblong, with a veiy oblique palm), the 5^'' Joint in 

 both gnathopods rather elongate; gnathopod 2 rather smaller than gnatlio- 

 pod 1. Peraeopods 3 — 6, 2*^ Joint slender, twice or (tigure) more than twice 

 as long as broad, the expansion forming a little lobe at top. üropods 1 and 2 

 with rami longer than peduncle, almost reachiug <i8 far as end of the long 

 uropod 3. üropod 3, outer ramus with 1^* Joint twice as long as peduncle, 

 2"^ Joint nearly '/, as long as l®*', inner ramus not much shorter^ than 

 1^* Joint of outer, both with numerous plumose setae on both margins. 

 Colour white or faintly flesh-toned. on exposure becoming more rosy. L. about 

 42 mm. 



Lake Baikal. Depth 1300 m. 



IH. E. capreolus (Dyb.) 1874 Gammarus c. + G.c.var. cJiloris, B. Dybowsky 

 in: Horae Soc. ent. Jloss . i'. 10 suppl. p. 87 1. 11 f. 1 | 1899 Echinogammarus capreolus, T. 

 Stebbingin: Tr. Linn. Soc. London, ser. 2 v.l p. 429 | 1%^'d Gammarus fiuviatilis (piirt.), 

 A.Della Valle in: F. Fl. Neapel, r. 20 p. 928. 



Peraeon segment 7 and pleon segments 1 — 6 with dorsal spines; on 

 perdeon segment 7 and pleon segments 1 — 3 the spines are very delicate, 

 occupying the hind margin in too close a row to be separated into groups; 

 on segments 4—6 they form 2 lateral groups, each with 2 — 5 spines, and 2 

 middle groups, each with 1 — 3 spines. Eyes rather large, slightly reniform, 

 wider below than above. Antenna 1 louger than the body, 1*** Joint stout, 

 nearly as long as 2"^ and 3*^ combined, flagellum 9 — 20 times as long as 

 peduncle, 64 — 95-jointed, accessory flagellum 5^ — 10-jointed. Antenna 2, 

 ultimate and penultiniate joints of peduncle subequal, much more slender 

 than 1^* Joint of antenna 1, flagellum 29 — 43-jointed, 2 or 3 times as long 

 as peduncle. Legs delicate, long, brittle. Gnathopod 1, iS^^ Joint slenderly 

 pii'iform (oblong in figure); gnathopod 2, 5*'* and Q>^^ joints longer but 

 narrower than in gnathopod 1, 6**' narrowly oblong, with short transverse 

 palm. Peraeopod 3 ouly a little shorter than peraeopod 4. Peraeopods 3 — 5, 

 2*^ Joint longer than broad, hind margin feebly convex, ending below in a 

 Short angle, üropod 1 longer than uropod 2, reaching end of uropod 3. 

 üropod 3, outer ramus twice as long as peduncle, its 2^ Joint '^ as long as l^S 

 inner ramus nearly as long as 1^* Joint of outer, both with plumose setae on 

 margins. Colour horn-yellow. L. 14 — 19 mm. — Vur. c/doris: eyes larger 

 and broadei-, legs more short and sturdy, 6*^ Joint of gnathopods 1 and 2 

 strenger and broader, 2^ Joint of peraeopods 3 — 5 broader and shorter, üro- 

 pods 1 — 3 shorter, colour gi'eenish, spotted with brown. L. U — 15 mm. 



Lake Baikal. Depth 100-200 m. 



17. E. ussolzewii (Dyb.) 1874 Gammarus ussolzevii, G. ussolzeu-ii, G. ussolzevi -f- 

 G. ussolzewii var. abyssorum, B. Dybowsky in: Horae Soc. ent. Ross., v. 10 suppl. j). 28, 

 89, 190 t.9 f. 2 I 1893 Gammarus fluviaiilis (part.)?, A. Della Valle in: F. Fl. Neapel, 

 u 20 p. 931 I 1899 Echinogammarus uzzolzetvii, T. Stebbing in: Tr. Linn. Soc. London, 

 ser. 2 u 7 p. 429. 



Peraeon segment 7 and pleon segments 1 — 6 with dorsal spines; on 

 peraeon segment 7 hind margin with 2 middle, 2 lateral and 2 marginal 

 groups of 3 or 4 spines each; pleon segments 1 — 3. spines of the gi'oups 

 more numerous, so as offen to form a continuous row on the hind raargin, 

 preceded by another row of 4 groups, 2 lateral and 2 marginal, with 3 

 or 4 spines each; segments 4 — 6 with 4 groußs, containing each 2 — 4 spines. 

 Eyes tolerably large, naiTOwly reniform, slightly widened below, black. Antenna 1 



