Gammarus, Poekilogaiiiinariis 477 



sinus below. Side-plates 1 — 4 ratlier small, 4*^^** not nearl}^ so broad as 

 deep. Pleoii segmeuts 2 and 3, postero-lateral coruers acute, but little 

 produced. Eyes constricted in the middle, sligbtly sigmoid, very dark. 

 Antenua 1 fully balf as long as body, 1^* Joint rather longer than 2"^ and 3^ 

 combined, flagellum nearly tlirice as long as peduncle, accessory flagellum about 

 (i-jointed. Antenna 2 shorter, flagellum in ä with no apparent calceoli. 

 Guatbopods 1 and 2 as in G. locusta, exeept that guatbopod 2 bas 6*^ Joint 

 in 9 rather sborter and in (S less obliquely truncated. Peraeopods 3 — 5 

 rather slender and elongate, 2*^ Joint in peraeopod 3 witb lower bind corner 

 nearly quadrate. Uropod 3, inner ramus not nearly as long as 1^* Joint of 

 outer, and witb fewer spines tban in G. locusta. Telson scarcely so long 

 as broad, lobes divergent, each with 3 apical spines, and on outer margin 

 1 spiue near apex and 1 near base. Colour semipellucid, pale greenish 

 with the usual pink markings faintly indicated. L. d scarcely over 6 mm, 

 5 smaller, 



North-Atlantic, Xorth-Sea and Skagerrak (South-Xorwaj-, in oyster-bed above sea- 

 level; in slialiow water at Christianiatjord; Isle of Arran; Shetlaiid; Belfast); Kattegat. 



G. tunetanus E. Sim. 1886 G. t., E. Simon in: Expl. Tunisie, Criist. p.G | 1893 

 G.ftuviatilis (part.)?, A. Della Valle in: F. Fl. Neapel, t\ 20 p. 768. 



Said to differ from G. pulex (p. 474) by having integument more sparingly and very 

 minutelj' i^unctate, head a little longer and in front a little attenuate, eyes more 

 elongate reniform, extending a little over the base of the antennae, accessory flagellum 

 of antenna 1 longer, 6-jointed, reachiug 6th Joint of primary flagellum, 3d, 4tli and 

 öth joints a little longer than the rest, equal to one another, flagellum of antenna 2 

 shorter, 8-jointed, all the joints a little longer than broad. From G. locusta it is 

 said to differ by the much shorter flagellum of antenna 2, with the joints fewer and 

 almost smooth. 



Tunis (Kerouan). 



45. Gen. Poekilogammarus Stebb. 



1899 Poekilogammarus, T. Stebbing in: Tr. Liun. Soc. London, ser. 2 v.l p. 428. 



In general like Gammarus (p. 460), but usually with dorsal hairs or 

 spinules on all Segments of peraeon and pleon, and head rostrate. Antenna 1 

 with peduncle longer tban peduncle of antenna 2, 3*^ Joint longer than 2*^. 

 Upper lip with wide, almost straight, apical margin; lower lip as in Axelboeckia 

 (p. 391), the principal lobes separated by wbat may be regarded as rudimentary 

 inner lobes. Maxiila 1, inner plate with about 6 setae. Maxillipeds, outer 

 plates not reachiug far along 3*^ Joint of palp. Gnathopod 1, 6^^ Joint larger 

 tban in gnathopod 2. üropod 3 with equal rami, both carry ing plumose 

 setae, outer ramus 1-jointed. - 



4 species. 

 Synopsis of species: 



/ Only pleon Segments 4 — 6 with dorsal spinules; head 



1 not rostrate 1. P. pictus . . . p. 478 



I Segments of peraeon and pleon with setules or spinules ; 

 ' head rostrate — • 2. 



i Peraeopod 5, 2d joiut slender 2. P. orehestes . p. 478 



\ Peraeopod 5, 2d Joint rather broad — 3. 



f Eostrum long, acute 3. P. talitrus . . p. 478 



\ Rostrum short, obtuse 4. P. araneolus . p. 479 



