484 Echinogammarus 



7. E. viridis (üyb.) 1874 Gammarus v. -j- G. v. var. ccmns -\- G. v. var. olivaceus, 

 B. Dybowsky in: Horae Soc. eut. Koss., u 10 suppl. j).95 t.6 1'.2; p.95 t.5 f.3, t.4 f.4; 

 p. 95 I 1899 Echinogammarus v., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.l p.429 | 

 1893 Gammarus fluviatilis (part.)?, A. Della Valle in: F. Fl. Neapel, r. 20 p. 931. 



Pleon Segments 1 and 2. spines usually arranged in 2 groups dose 

 to liind margin (wanting on segment 1 in var. ca)nix, and on both segments 

 in var. olivaceus); segment 3, spines in 2 — 4 transverse series, on tlie hind- 

 most forming oblique lateral groups, but raiddle groups almost parallel to 

 the bind margin, in the front rows middle groups sometimes wanting; 

 segment 4, spines in 1 or 2 series, consisting eacb of 2 middle and 2 lateral 

 groups; Segments 5 and 6 each with only 1 such row. The ridges or humps 

 generally feeble, in young specimens scarcely indicated; number of spines 

 in each group variable, encreasing with age. Eyes reniform, black. Antennae 1 

 and 2, gnatbopods 1 and 2 and peraeopods 3—5 differing little from those 

 of E. lividus (p. 483), but antenna 1, accessory flagellum 4— 6-jointed, antenna2, 

 ultimate Joint of peduncle more decidedly longer than penultimate, gnatlio- 

 pod 1, 6*^'' Joint thrice as long as 5**", the 2 combined longer than 5*^ and 

 6*'^ of gnathopod 2, which are comparatively wider than in E. lividus, as is 

 also 2^ Joint of peraeopods 3 — 5. Antenna 1 comparatively shorter, with 

 fewer joints to the flagellum in tiie two varieties. Uropod 1 almost reaches the 

 end of the inner ramus of uropod 3, which is tolerably long, the outer ramus 

 about 3 — 5 times as long as (figure; in text: ^/^ — ^4 longer than) the inner, 

 carrying marginal spines and simple setae. Telson (in figure) less elongate than 

 in E. lividus. Colour varying from bright grass-green to dark olive-green, 

 appendages red, horn-yellow to horu-brown. L. 24 — 31 mm. 



Lake Baikal, shore to 20 ni ; River Angara. 



8. E. oyaneus (Dyb.) 1874 Gammarus c, B. Dybowsky in: Horae Soc. ent. 

 ßoss., u 10 suppl. p. 92 I 1899 Echinogammarus c, T. Stebbing in: Tr. Linn. Soc. 

 London, ser. 2 v.7 p.429 1 1893 Gammarus pungens (part.)?, A. Della Valle in: F. Fl. 

 Neapel, f. 20 p. 928. 



Pleon segment 1 with 2 — 6 delicate spinules on bind margin; segment 2 

 with 6 — 8 somewhat more conspicuous, but still setiform spines on bind margin; 

 segment 3, whole dorsal surface set with long setae, among which the spines, 

 if present, completely disappear; segments 4 — 6 less setose, spines stronger, 

 on segment 4 forming 2 middle and 2 lateral groups, on segments 5 and 6, 

 1 median and 2 lateral groups, number of spines to a group 2 — 4. Eyes 

 slightly reniform, black. Antenna 1 about \'^ as long as body, flagellum 

 24 — 35-jointed, accessory flagellum 4- or 5-jointed. Antenna 2, flagellum 

 11 — 13-jointed. Gnathopod 1 piriform, gnathopod 2 oblong, Gnathopod 1 

 in ö longer and broader than gnathopod 2, in 9 rather broader but not 

 longer. Peraeopods 3 — 5, 2^ Joint tolerably broad, bind margin slightly 

 convex, carrying 8 — 10 short setae, ending in a projecting acute angle. Uropods 1 

 and 2 about reaching end of inner ramus of uropod 3. uropod 3 moderately 

 long, outer ramus 3 or 4 times longer than inner, both with simple marginal 

 setae. Colour bluish. L. 18 mm. 



Lake Baikal. Near the shore, under stones. 



9. E. ochotensis (F. Brandt) 1851 Gammarus 0., F.Brandt in: Middendorff, 

 Reise Sibirien, i;. 2i p. 140 t.6 f. 31a — c | 18fi2 Gr. 0., Bäte, Cat. Ajnphip. Brit. Mus., 

 p. 216 t. 38 f. 5 I 1899 Echinogammarus 0., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 

 v.7 p.429 I 1893 Gammarus marinus (part.), A. Della Valle in: F. Fl. Neapel, n20 p.762. 



