462 Gammarus 



{ 



. Eyes Short, oval 18. G. ischnus p. 470 



Eyes long, retort-shaped 19. G. placidus . . . . p. 470 



I Gnathopod 2, 6tli Joint greatly expandeddistally 20. G. platycheir . . . . p. 471 

 21 < Gnathopod 2, 6th Joint not greatly expanded 

 l distally — 22. 



{Antenna 1, Ist joint not as long as 2d and 3d 

 combined 21. G. pungens p. 471 

 Antenna 1, Ist joint as long as 2d and 3d 

 combined — 23. 



l Pieon Segments 4 — 6. dorsal spinales numerous 22. G. marinus p. 472 



\ Pleon Segments 4 — 6, dorsal spinales few . . 23. G. simoni p. 473 



j Pleon Segments 4 — 6 dorsally hairy 24. G. duebenii .... p. 473 



\ Pleon Segments 4 — 6 not dorsally hairy — 25. 



{Antenna 1, accessory flagellum with not more 

 than 4 joints — 26. 

 Antenna 1, accessory flagellum with more than 

 4 joints — 29. 



iPeraeopod 5, 2d joint with lower hind corner 

 rounded 25. G. pulex p. 474 

 Peraeopod 5, 2d joint with lower hind corner 

 not roanded — 27. 



{ Uropod 3, inner ramas only half as long as oater 26. G. delebeequei . . . p. 475 

 Uropod 3, inner ramus mach more than half 

 as long as oater — 28. 



{Gnathopod 1, 6*^ joint rather longer than that 

 of gnathopod 2 * . . 27. G. hyacinthinus . . p. 475 

 Gnathopod 1, 6tli joint not longer than that of 

 gnathopod 2 28. G. syriacus . . . . p. 475 



j Eyes renif orm 29. G. locusta p. 476 



{ 



Eyes constricted in the middle 30. G. camylops . . . . p. 476 



1. G. guernei Chevreux 1889 G.g., Chevreux in: Bull. Soc. zool. France, v.li 

 p.294f. I 1893 G. pungens (part.), A. Della Valle in: F. Fl. Neapel, v.20 p.764. 



In form resembling G. pulex (p. 474). Pleon segments 4—6 with 

 small dorsal fascicles of spines, 6 spines on segment 4, 8 on segment 5, 

 2 on segment 6. Head (in figure) with lateral angles scai'cely at all prominent. 

 Side-plates 1 — 4 rather deep. Pleon segments 1 — 3, postero-lateral angles 

 acute. Eyes small, reniform. Antenna 1 not quite half as long as body, 

 peduncle not long, 2^ joint rather shorter than 1^*, and 3<^ than 2^, flagellum 

 quite smooth, 19-jointed, accessory flagellum 1-jointed. Antenna 2 considerably 

 shorter, flagellum without setae, 9-jointed. Gnathopods 1 and 2 similar, 

 but 5*^ and 6**^ joints longer in gnathopod 2, 6*^ joint oblong, palm well 

 defined, short, a little oblique. Peraeopod 1, 4*^ joint long and wide, strongly 

 setose on Mnd margin, 5*^ Joint much nart'ower and shorter, likewise setose. 

 Peraeopod 2 shorter and slighter, not setose. Peraeopods 3 — 5 rather long, 

 2^ Joint well expanded, oval. Uropod 3 reaching far beyond the others, 

 outer ramus very long, with small 2^ Joint, inner ramus rudimentaiy, oval. 

 Telson very short, each broadly oval lobe having a fascicle of spines at 

 middle of outer margin, and another of 5 spines at apex. L. 6 mm. 



Azores (Flores). Torrents. 



2. G. abbreviatus 0. Sars 1894 G. a., G. 0. Sars in: Bull. Ae. St.-Petersb., 

 ser. Sulp. 365. 



