Echinogammarus 487 



accessory flagellum with 12 joints in Q, 10 in c?. Antenna 2, ultimate 

 Joint of peduncle rather shorter tban penultimate, flagellum 28-jointecl, with 

 calceoli. Gnathopods 1 and 2 as in El. fuscus. Peraeopods 3 — 5, 2*^ Joint 

 tolerably broad, but narrower and louger tban in E. fuscus. Cropods 1 

 and 2 reaching middle of uropod 3. üropod 3, outer ramus strong, with 

 onlj simple setae on outer margin, plumose setae also on inner; inner ramus 

 narrow, % as long as outer, with plumose setae on both margins. Telson 

 elongate, (in figure: each lobe with 1 spiue high up on outer margin, 1 low 

 down on inner, 3 on narrow apex). Colour briglit violet-brownish or dark 

 grey, with bright olive-green spots, appendages banded. L. about 23 mm. 



Lake Baikal. Depth 30—100 m. 



14. E aheneus (Dyb.) 1874 Gammarus a. -\- G. a. var. setostis + 6r. a. suhvar. 

 miniatus -\- G. a. suhvar. succineus, B. Dybowsky in: Horae Soc. ent. Ross., f. 10 suppl. 

 p. 65, 66; t. 7 f.], 2; t. 6 f. 3 I 1899 Echinogammarus a., T. Stebbing in: Tr. Linn. 

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

 F. Fl. Neapel, v. 20 p. 927. 



Pleon Segments 1 — 6 armedwith spines, varying in number and arrange- 

 ment; segment 1 with 1 or 2 cross-rowsof spines, segmeut 2 with 2 — 4cross-rows, 

 Segment 3 with 4 or 5. segment 5 with 1 or 2, segment 6 with 1 cross-row of 

 spines; segment 4 not specified. Besides the spines occur setae, which sometimes 

 take the place of the spines or conceal them. Pleon segments 1 — 3 having 

 the lateral lobes distinctly marked off; also on lower margins of side-plates 

 there are usually setae, few or whole fascicles. p]yes reniform or biscuit- 

 shaped, often slightly widened below, black. Antenna 1 nearly or quite as 

 long as body, l^^ Joint little or not longer than 2*^, 3*^ not very short, flagellum 

 41 — 116-jointed, accessory flagellum 7 — 13-jointed. Antenna 2, ultimate 

 Joint of peduncle long, longer than penultimate, flagellum 20 — 33-jointed, 

 with calceoli. Gnathopod 1, d^^ Joint piriform, larger than the oblong 6*^ 

 of gnathopod 2. Peraeopods 3 — 5, 2*^ Joint moderately broad, hind margin 

 slightly convex or somewhat concave, ending below in a little angle, öro- 

 pod 1 not reaching middle of uropod 3. Uropod 3 long and strong, outer 

 ramus 2-jointed, more than twice as long as inner, slightly curved inward, 

 with only simple setae on outer margin; inner ramus with fascicles of simple 

 setae interspersed with plumose ones on its margins. Telson (in figure) as in 

 E. murinus. Colour red or yellow. L. reaching about 37 mm. 



Lake Baikal. Depth 50 — 500 m. 



15. E. sarmatus (Dyb.) 1874 Gammarus s., B. Dj'bowsky in: Horae Soc. ent. 

 Ross., V. 10 suppl. p. 86 t. 1 f. 3; t. 8 f. 4 | 1899 Echinogammarus s.. T. Stebbing in: 

 Tr. Linn. Soc. London, ser. 2 v. 7 p. 429 | 1893 Gammarus fluviatilis (part.), A. Della 

 Valle in: F. Fl. Neapel, f. 20 p. 930. 



g unknown. — d. Peraeon segment 7 and pleon segments 1 — 6 

 with dorsal spines, forming a Single cross-row on hind margin, formed of 

 2 lateral groups with 2 — 5 spines in each, and 2 middle groups with 1 — 4 

 spines in each. Eyes retort-shaped, almost pointed above, concave in front, 

 the widened lower part with lower margin slightly concave, white, becoming 

 rosy on exposure. Antenna 1 longer than body, 1^*^ Joint long, 2*^ and 3* 

 successively a little shorter, flagellum thrice as long as peduncle, 130-or 

 131-jointed, accessory flagellum 39-jointed. Antenna 2 very little shorter 

 than antenna 1, ultimate Joint of peduncle longer than penultimate, 

 flagellum 110 — 115-jointed, twice as long as peduncle. All the legs long 



