504 Carinogammarus 



prominent, oval, a little wideued ,below, red. Antenna 1 rather less than 

 ^U as loDg as body, twice as long as antenna 2, 1^* Joint stout, flagellum 

 27 — 34-jointed, accessory flagellum 4- or 5-jointed. Antenna 2, flagellum 

 9-joiuted. Gnathopods 1 and 2 seemingly almost as in C. pulchellus (p. 503), 

 but 6*^ Joint of gnathopod 1 more piriform, and palm in gnathopod 2 

 less completely ti-ansverse. Peraeopod 3, 2*^ Joint carried in motion of 

 the auimal at an acute angle to the long axis of the body, the expansion 

 ending in a lobe below. Peraeopod 5, 2^ Joint little longer than broad, its 

 greatest breadth being at the distal end. üropods 1 and 2 not long, reaching 

 nearly to end of uropod 3. üropod 3, inner ramus longer than 1^* Joint 

 of outer, The deeply cleft telson is described as long. Colour white. L. reaching 

 about 17 mm. 



Lake Baikal. Depth 50—100 m. 



5. C. rhodophthalmus (Dyb.) 1874 Gammarus r. -{- G. r. var. microphthalmus, 

 B. Dybowsky in: Horae Soc. ent. Ross., r. 10 snppl. p. 116, 117 1. 14 f. lO 1 1899 Carino- 

 gammarus r., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.7 p. 429 | 1893 Gammarus 

 fluviatilis (part.)?, A. Della Valle in: F. Fl. Neapel, u 20 p. 930. 



Peraeon segments 6 and 7 and pleon segments 1 — 4 or 1 — 5 with 

 a weakly indicated median tubercular carina, pleon segment 6 with 2 groups 

 of delicate spinules; (in var. nmrop/itJialrnns carina extending to pleon segment 

 5, or only to 3 ; pleon segment 6 with a pair of setae). Head, front shortly 

 produced, obtusely triangulär. Side-plates 1 — 4 setose on lower margin, 

 4*^ broad, well emarginate; pleon segment 3, postero-lateral corners quadrate. 

 Eyes very large, prominent, broadly oval, occupying nearly half the lateral 

 surface of head, the front part turued forward and inward, ruby-red, (in the 

 variety much smaller, but still tolerably large, black or reddish black). 

 Antenna 1 half (in the variety more than half) as long as body, twice as long 

 as antenna 2. l***^ Joint stout, flagellum 37 — 44- (in the variety 8 — 34-) 

 jointed, accessory flagellum 3 — 5-jointed. Antenna 2, flagellum 7 — 11-jointed. 

 Gnathopods 1 and 2 small, subequal, 5*** Joint not elongate, 6*'* piriform in 

 gnathopod 1 (in figure oblong, with oblique palm ; in the variety described as 

 oval); 6*^^ Joint in gnathopod 2 oblong, narrower than in gnathopod 1, palm 

 much less oblique. Peraeopods 3 — 5, 2*^ Joint with the expansion abruptly 

 narrowing below, though less so in peraeopod 5 than in 3 and 4; in all 

 the bind margin armed with long setae. Uropod 3. inner ramus about as 

 long as 1^* Joint of outer (in variety the rami subequal). Colour white or 

 bright yellow. L. 14 — 20 mm. 



Lake Baikal. Depth 8—100 m. 



6. C. caspius (Fall.) 1771 Oniscus c, Pallas, Keise ßiiß.. v. l p. 477 I 1841 

 Gammarus c, Eichwald in: N. Mem. Soc. Moscou, v.7 p. 230 | 1894 G. c, G. O. Sars 

 in: Eiill. Ac. St.-Petersb., ser. 5 v.l p. 210 t. 7 | 1899 Carinogammarus c, T. Stebbing 

 in: Tr. Linn. Soc. London, ser. 2 ?;. 7 p. 430 | 1862 Gammarus semicarinatus, Bäte, 

 Cat. Amphip. Brit. Mus., p. 204 t. 36 f. 3 | 1893 G. fluviatilis (part.), A. Della Valle in: 

 F. Fl. Neapel, v. 20 p. 763. 



Peraeon segment 7 sometimes slightly carinate and produced to a small 

 tooth; pleon segments 1 — 3 strougly carinate, each produced into a large 

 acute backward pointing tooth; segments 4 and 5 each with an elevated 

 flat-topped dorsal tubercle, capped by 2 pairs of spines, segment 6 with 1 

 pair of subdorsal spinules. Head, rostrum almost obsolete, lateral lobes broad, 

 obtusely truncate. Side-plate 4 much the largest. Pleon segments 2 and 3, 

 postero-lateral corners acute. Eyes oblong reniform, sometimes dark. Antenua 1 



