Echinogammarus 493 



26. E. parvexii (Dyb.) 1874 Gammarus j)., B. Dybowsky in: Horae Soc. ent. 

 Eoss., V. 10 siippl. p. 81 t. 10 f. 2 I 1899 Echinogammarus p., 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. 929. 



Pleon Segments 1 — 6 each with 4 groups of dorsal spines on elevations 

 of the bind raargiii. the middle groups each with 1 or 2 spines, the lateral 

 each with 2 — 4. Eyes tolerably large, biscuit-shaped or reniform, wide apart 

 above, black. Antenna 1 nearly twice as long as body,thrice as long as antenna 2, 

 1^* Joint not as long as 2*^ and 3'^ combined, flagellum 7 — 9 times as long as the 

 thin peduncle, 310-joiuted, accessory flagellum 17-jointed. Antenna 2, ultimate 

 Joint of peduncle longer than penultimate. flagellum shorter than peduncle, 

 26-jointed. Gnathopod .1, 5^^ Joint as broad as long, 6*^ very broadly pii-iform, 

 the basal half tumid, finger strongly curved. Gnathopod 2, 6^'^ Joint long 

 and narrow, palm short. alniost transverse. Peraeopods 3 — o, 2*^ Joint narrow, 

 in figure of peraeopod 5 more than twice as long as broad, bind margin 

 flatly concave, produced to a subacute poiut. Uropods 1 and 2 long, reaching 

 nearly the middle of uropod 3, rami longer than peduncle. Cropod 3, outer, 

 ramus without plumose setae on outer margin, 2*^ Joint between 7? and ^/g 

 as long as 1^*, inner ramus % as long as 1*** Joint of outer. Colour orauge- 

 yellow. L. about 25 mm. 



Lake Baikal. Depth 170 ux. 



27. E. polyarthrus (Dyb.) 1874 Gammarus longicornis (non J. C. Fabricius 

 17791) -f- G. l. var. p., ß. Dybowsky in: Horae Soc. ent. Ross., v. 10 suppl. p. 79; p. 80 

 1. 10 f. 2b', c' ! 1899 Echinogammarus p., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 

 v.7 p. 429 i 1893 Gammarus calcaratus (part.)?, A. Della Valle in: F. Fl. Neapel, 

 i;.20 p.929. 



Pleon Segments 1 — 6 each with 4 groups of dorsal spines on ridge- 

 like elevations of the bind margin, the 2 middle groups each with 2 — 4 spines, 

 the lateral with 2 — 6, except on segment 6, where there are only 4 spines 

 for the 4 groups; also on segmeuts 4 and 5 the middle groups are weakly 

 developed. Eyes large, little deeperthan broad, reniform, slightly widened below, 

 narrowed above, black or reddish. Antenna 1 in ö longer than the body, 3 — 4 times 

 as long as antenna 2, flagellum 5 — 8 times as long as the stout peduncle, 250 — 340- 

 jointed, accessory flagellum 16-jointed. Antenna 2, ultimate Joint of peduncle 

 longer than 1^* Joint of antenna 1, flagellum shorter than peduncle, 25 — 29- 

 jointed. Gnathopod 1, 6**^ Joint piriform base not tumid. Gnathopod 2, 6*^ Joint 

 oblong. Peraeopods 3 — 5, 2^ Joint not very broad, bind margin flatly concave, 

 endiug in a short, projecting point. üropods 1 and 2 reaching middle of 

 uropod 3. Cropod 3, inner ramus about % length of outer, both with plumose 

 setae on both öiargins. Colour brighter or darker reddish yellow. L. 32 mm. 



Lake Baikal. Depth 170— 700 m: the so-called Tarietj, from 300— 700 m. 



E. mutilus (Abildg.) 1789 Gammarus m., Abildgaard in: 0. F. Müller, Zool. 

 Dan., ed. 3 v. 3 p. 60 t. 116 f. 1—11 \ 1888 G.m., T. Stebbing in: ßep. Voy. Challenger, 

 r. 29 p. 56 I 1793 Cancer (Gammarellus) m., J. F. W. Herbst, Naturg. Krabben Krebse, 

 i'. 2 p. 120 t. 35 f. 7 I 1893 Gammarus locusta (part.), A. Della Valle in: F. Fl. Neapel, 

 V. 20 p. 759. 



Peraeon segment 7 and pleon segments 1 — 3 furnished dorsally with backward 

 directed spines on hind margin. Antennae 1 and 2 subequal, flagellum long in both. 

 Accessory flagellum of antenna 1 very long, 24-jointed. Peduncle of antenna 2 reaching 

 beyond that of antenna 1. Uropod 3, peduncle short, rami rather long, nearly equal, 

 fringed with long setae. 



North-Atlantic (Farö Isles). On the shore. 



