Gammarus 471 



Body exceedingly slender, less compressed than in G. ischuus; pleon 

 Segments 4 — 6 each with 1 median and 2 lateral fascicles, the latter containing 

 each 4 spinules in segment 4, 3 in segment 5, 2 in segment 6. Head, 

 lateral lobes conspicuously acute, the point sometimes slightly deflexed. Side- 

 plates 1 — 4 not very large, 1^* quadrangular, 2*^ and 'M slightly narrowed 

 distally, 4^^ at least as broad as deep. Pleon Segments 2 and 3, postero- 

 lateral corners acutely quadrate. Eyes dark, very narrow, deep, below a 

 little inflated and bent forward. Antenna 1 slender, nearly ^/^ as long as 

 body, 2^ Joint fully as long as l***^, flagellum twice as long as pedimcle, 

 about 33-jointed, accessory flagellum 7-jointed. Antenna 2 shorter, more 

 densely setose, ultimate Joint of peduucle (in figure) longer than penultimate, 

 flagellum about 16-jointed. Gnathopods 1 and 2 in Q not powerful, setose, 

 subequal, but 5*^ and 6^^^ joints in gnathopod 1 rather shorter, 6^^ oblong 

 oval, palm rather oblique, 6^^^ Joint in gnathopod 2 oblong, palm neai'ly 

 trausverse (in young d gnathopod 2 considerably larger than gnathopod 1). 

 Peraeopods 1 and 2 rather slender, 1^^ the longer. Peraeopods 3 — 5 stouter, 

 rather long, often reflexed, 2<^ Joint narrowly oblong oval, without a free 

 Corner, in peraeopod 5 of same size and shape as in 4^^. Uropods 1 and 2, 

 rami spinöse. Uropod 3 exceedingly long, outer ramus nearly 4 times as long as 

 peduucle, sublinear, with raany fascicles of spines and a few setae on both 

 margius, 2** joiut spiniform, inner ramus extremely small, not half as long 

 as peduucle. Telson short, nearly twice as broad as long, lobes not divergent, 

 outer margin almost angularly bent below its 1 spinule, apex obtusely truncated, 

 carrying 1 spinule. L. o 13 mm. 



Caspian Sea. J^epth 4 — 75 ra. 



20. G. platyeheir O. Sars 1896 G. p., G. O. Sars in: Bull. Ac. St.-Petersb., 

 ser. 5 V.4 p. 460 t. 8 f. 14—17. 



d(?). Body rather robust, back broadly vaulted, pleon segments 4 — 6 

 dorsally each with 2 adjacent spinules, segment 6 also with a spinule on 

 either side. Head, lateral lobes rather broad, vertically truncated. Side- 

 plates 1 — 4 rather deep, setose, 1^* smallest, 1*^* and 2^ distally narrowed, 

 3*^ much larger, oblong, 4*^ nearly as broad as deep. Pleon segments 2 

 and 3, postero-lateral corners quadrate, 2*^ on anterior lateral margin closely 

 friuged with delicate, curved setae. Eyes not large, oval reniform. Antenna 1 

 very short. not ^/^ as long as body. l'^* Joint as long as 2'^ and 3*^ combined, 

 flagellum shorter than peduucle, 12-jointed, accessory flagellum 4-jointed. 

 Antenna 2 as long or a little longer, flagellum ll-jointed. Gnathopod 1 

 much the smaller. Gnathopod 2, 5^^ joiut small, 6'^'^ very large, flattened, 

 gradually expandiug to the long, oblique, evenly curved palm, which is densely 

 fringed with spiniform setules, and defined by 3 streng spines, among which 

 the tip of the long falciform fiuger closes down. Pi^raeopod 2 more setose 

 than peraeopod 1. Peraeopod 3 much shorter than peraeopods 4 and 5, 

 2^ Joint in peraeopods 3 and 4 narrowed below, without a free corner, in 

 peraeopod 5 much larger, oblong oval, bind margin closely fringed with setules. 

 üropod 3 reaching beyond the others, outer ramus subfoliaceous, twice as long 

 as peduucle, fringed with setae, 2*^ Joint very small," inner ramus about ^/g 

 as long as outer, with 2 spiuules at apex. Telson about as long as broad, 

 cleft not quite to the base, the broad lobes distally divergent, with 3 spinules 

 on the blunt apex of each. L. 16 mm. 



Caspian Sea (uiouth of Volga). 



21. G. pungens M.-E. 1840 G. p., H. Milne Edwards, Hist. nat. Crust., v.3 

 p.47 1 1893 G.p. (part.), A. Della Valle in: F. Fl. Neapel, r. 20 p. 764 t. 24 f. 35 [ 1862 



