Echinogammarus 483 



5. E. maaekii (Gerslf.) 1858 Gammarus m., Gerstfeldt in: Mem. pres. Ac. 

 St.-Petersb., v. 8 p. 283 | 1862 G. m., Bäte, Cat. Amphip. Brit. Mus., p. 217 t. 38 f . 8 | 

 1874 G. m., B. üybowsky in: Horae Soc. ent. Boss., i'. 10 siippl. p. 97 j 1888 G. m., 

 T. Stebbing in: Rep. Voy. Challenger, r.29 p. 309 | 1899 Echinogammarus m., T. Stebbing 

 in: Tr. Linn. Soc. London, ser. 2 v.l p. 429 | 1893 Gammarus pungens (part.), A. Della 

 Valle in: F. Fi. Neapel, p. 20 p. 764. 



Pleon Segments 1 — 6 with spines pectinately arranged on ridges; on 

 Segment 1 are 2 oblique lateral ridges, each with 5 — 8 spines, on Segments 2 

 and 3 the lateral ridges are longer, each with 7 or 8 spines commonly 

 divided into two sets. of which the front is smaller than the hinder, also there 

 are often 2 little median humps, or on segment 3 two pairs of them, each with 2 or 

 3 spines; Segments 4 — 6 have the ridges short, each with 3 — 6 spines, 

 and 2 little median humps, each with 1 or 2 spines. Eyes narrowly reniform, 

 black. Antenna 1 about ^j^ as long as body, 1^* Joint shorter than ultimate 

 Joint of peduncle of antenna 2, flagellum 40 — 54-jointed, accessory flagellum 

 4- or 5-jointed. Antenna 2, flagellum 14 — 17-jointed. Gnathopods 1 and 2, 

 6^^ Joint piiiform, larger in gnathopod 1 than in gnathopod 2 (authors' accounts 

 differ). Peraeopods 3 — 5, 2*^ Joint moderately broad, bind margin sinuous, 

 endiug in blunt, little projecting corner. üropod 1 reaching end of peduncle 

 of uropod 3. Uropod 3 long, ^j^ as long as body, distinguished by paucity 

 of setae, which are short and scattered, inner ramus scarcely 7io ^^ long 

 as outer. Colour, body green, appendages red. L. about 28 mm. 



River Angara at Irkutsk; Lake Baikal, depth '/a — 2 m. 



6. E. lividus (Dyb.) 1874 Gamnmrus l., B. Dybowsky in : Horae Soc. ent. Ross., 

 V. 10 suppl. p. 68 t. 6 f. 1 I 1899 Echinogammarus l., T. Stebbing in : Tr. Linn. Soc. 

 London, ser. 2 v.l p. 429 \ 1893 Gammarus pungens (part.), A. Della Valle in: F.Fl. 

 Neapel, u20 p. 929. 



Pleon Segments 1 — 6 with spines, segment 1, bind row in 4 groups, 

 each with 4—6, front in 2 gTOups, each with 4 spines; segment 2, bind 

 row as in segment 1, preceded by 3 rows, each forming 2 widely separated 

 groups; segment 3 like segment 2, but with occasional addition of some 

 intermediate groups; segment 4, bind row with a middle and 2 lateral 

 groups, front with 2 middle and 2 lateral groups; Segments 5 and 6 each 

 with a middle and 2 lateral gi'oups in 1 row. Eyes flat, long reniform, 

 below a little widened and truncate or slightly emarginate, black. Antenna 1 

 about '^l^ as long as body, peduncle sborter than peduncle of antenna 2, 

 1^* Joint rather shorter than 2*^, flagellum with 46 — 60 joints in o , 52 — 70 in 

 d, accessory flagellum 5 — 9-jointed. Antenna 2, ultimate Joint of peduncle 

 slightly louger than penultimate, flagellum shorter than both combined, with 

 6 — 20 joints in 9 , 16 — 26 in d, can-ying calceoli in both sexes. Gnathopod 1, 

 5**» Joint as broad as long, about % as long as the naiTowly piriform 6*^. 

 Gnathopod 2, 5*^ and 6*^ joints together as long as those of gnathopod 1 

 but much narrower, 5*^ Joint '^i^ as long as the narrowly oblong 6*^, which 

 has a Short, well defined, almost ti'uncate palm. Peraeopods 3 — 5, 2*^ Joint 

 moderately broad, bind margin slightly convex or sinuous, euding often in 

 a minutely produced angle. Uropod 1 reaching ^3 of uropod 3, which is rather 

 long, outer ramus 6 or 7 times as long as inner, with spines and fascicles 

 of long simple setae on both margins. Telson (in figure) much longer 

 than broad, each lobe with a spine high up on outer margin and 3 spines 

 on the narrow apex. Colour violet-blue or greenish violet, often with metallic 

 glance, antennae 1 and 2 and uropod 3 red or violet-brown. L. 40 mm. 



Lake Baikal. Depth 1—10 m. 



31* 



