464 Gammarus 



Doaiiy iilike in both gnathopods. üropod 3, rami long, lanceolate, fringed 

 witb long plumose setae, outer with slender, almost spiniform 2*^ Joint, 

 inner as long as l*** Joint of outer. Telson, each lobe nearly thrice as long 

 as broad. L. 10 — 12 mm. 



Viueyard Sound [ünited States of America]. At surface, usiially among floating 

 sea-weed. 



5. G. obesus O. Sars 1894 G. o., G. O. Sars in: Bull. Ac. St.-Petersb., ser. 5 

 v.l p. 368 t. 15. 



Body extremely short and stout, more so than in any otlier knowu 

 Gammarus, dorsally smootli, except for a pair of very small spinules on pleon 

 Segment 6. Head, lateral lobes little prominent, evenly rounded. Side- 

 plates 1 — 4 large and deep, distally fringed with setae, 1^* rather broadly 

 expanded distally, 4**^ not as broad as deep. Pleon segments 2 and 3, 

 postero-lateral corners obtusely quadrate. Eyes oval, reniform, not large. 

 Antenna 1 about ^/g length of body, 1^* Joint large, longer than 2*^ and 3** 

 combined, flagellum rather longer than peduncle, 15-jointed, accessory flagellum 

 2-jointed. Antenna 2 rather shorter, flagellum as long as ultimate and pen- 

 ultimate joints of peduncle combined, 7-jointed. Gnathopods 1 and 2, 6*^ Joint 

 oblong oval, palm well defined, not very oblique, more so in (S than in Q , 

 gnathopod 2 a little stronger than gnathopod 1, and both gnathopods rather 

 stronger in 6 than in o . Peraeopods 1 — 5 rather strong, densely setose, 

 5*^ Joint Short, finger strong. Peraeopods 3 and 4, 2^ Joint narrowing 

 distally, so that the lower bind corner is not free. Peraeopod 5, 2*^ Joint 

 widely expanded, widened distally, with broadly rounded lobe, üropods 1 

 and 2 with only apical spines. Üropod 3 unusually short and stout, reaching 

 little beyond the others, outer ramus scarcely longer than peduncle, carrying 

 plumose setae, 2'^ Joint minute, inner ramus scale-like, with 1 apical spine. 

 Telson much broader than long, each lobe having 1 spine and 2 setules 

 on the narrowly truncated apex. L. o 8, c? 9 mm. 



Caspian Sea. Shallow water. 



6. G. macrurus 0. Sars 1894 G. m., G. 0. Sars in: Bull. Ac. St.-Petersb., ser. 5 

 V. 1 p. 350 t. 10 f. 17—27. 



9 . Body slender, dorsally smooth except for a pair of very small 

 spinules on pleon segment 6. Head, lateral lobes broadly rounded, prominent. 

 Side-plates 1 — 4 rather large, fringed with scattered setules; P* a little 

 expanded, 4:^^ very large, as broad as deep. Pleon segments 2 and 3, postero- 

 lateral corners produced to a rather obtuse point. Eyes not very large, 

 oblong oval, dark. Antenna l scarcely more than ^4 length of body, l«* Joint 

 large, nearly twice as long as 2*^ and 3^ combined, flagellum about as long 

 as peduncle, 6-jointed, accessory flagellum 3-jointed. Antenna 2 a little 

 shorter, antepeuultimate Joint of peduncle wide, projecting, ultimate Joint 

 shorter than penultimate, flagellum 4-jointed. Gnathopods 1 and 2 small 

 and feeble, 6^^ Joint subequal to 5*^ in length and scarcely broader, these 

 2 joints being rather longer, but not wider, in gnathopod 2 than in gnatho- 

 pod 1. Peraeopods I and 2, 4*^^ Joint rather expanded, this and the 5*^ 

 setose. Peraeopod 3, 2^ Joint rounded quadrangular. Peraeopod 4, 2<^ Joint 

 narrower and scarcely longer, naiTowed close to distal end. Peraeopod 5, 

 2^ Joint much larger, oval, hinder expansion produced downward in a broadly 

 rounded lobe, üropods 1 and 2, rami equal, narrow. üropod 3 long. 



