Gammarus 463 



Body rather short and stout, pleon segment 4 smootb, Segments 5 and 6^ 

 each witli 1 or 2 veiy small dorsal spinules. Head, lateral lobes slightly 

 prominent, evenly rounded. Side-plates 1 — 4 distally conspicuously crenulate 

 and setose, 1^* obliquely expanded below, 4*^^ very broad. Pleon Segments 2 

 and 3, postero-lateral corners acute. Eyes oval reniform. Antenna 1 very short, 

 not ^/^ as long as body, P* Joint large, longer tban 2^ and 3^ combined, flagellum 

 about as long as peduncle, 9-jointed, accessory flagellum 4- or 5-jointed. 

 Antenna 2 rather longer, setose, ultimate Joint of peduncle shorter tban 

 penultimate, flagellum about 7-jointed. Gnathopods 1 and 2 in 9 similar, 

 2^ slightly tbe larger, 6*^ Joint oblong oval, palm rather oblique, pretty well 

 defined. Gnathopods 1 and 2 in d sti-onger, much more unequal, 6*^ Joint 

 in gnathopod 1 narrowing distally, palm more oblique, in gnathopod 2 much 

 larger, oblong oval, with the usual spine in middle of palm. Peraeopods 1 

 and 2 strongly built, densely setose, 4*^ Joint large and expanded. Peraeo- 

 pods 3 — 5, 2^ Joint expanded, rounded quadrangular in peraeopod 3, expanded 

 above, tapering below in peraeopod 4, much larger and regularly oval in 

 peraeopod 5, produced downward behind in nari'owly rounded lobe, üropods 1 

 and 2 reaching beyond peduncle of uropod 3. üropod 3 not very long, 

 outer ramus densely setose, with small but obvious 2'^ Joint, inner ramua 

 about as long as the short peduncle. Telson about as long as broad, each 

 lobe with 3 apical spines, otherwise smooth. L. g 12, ö 13 mm. 



Caspian Sea. Among Zostera. 



3. G. annulatus S. I. Sm. 1873 G. a., (S. I. Smith in:) A. E. Verrill in: ßep. 

 U. S.Fish Comra., v. 1 p. 557 ] 1893 G. locusta (part.), A. Della Valle in: F. Fl. Neapel, 

 V. 20 p. 760. 



Pleon segment 4 with median fascicle of 2 large and 2 small spines, 

 Segments 5 and 6 with lateral fascicles as well as median. Head, lateral 

 lobes truncate, somewhat prominent. FJyes scarcely renifonn, lower border 

 remote from lateral lobes of head. Antenna 1 shorter than antenna 2. 

 Antenna 2, ultimate Joint of peduncle longer than penultimate, flagellum 

 slender, with rather elongate joints. Gnathopod 1, 6*^ Joint rather elongated, 

 palm very oblique. Gnathopod 2, 6*^ Joint very naiTow, elongated, sub- 

 cylindrical, slightly flattened on inner side, palm longitudinal, scarcely 

 distinct from bind margin. Colour gi-eyish white, bind margins of Segments 

 annulated with brown, red spots on some of the pleon segments. L. 12 — 18 mm. 



North- Atlantic (New Haven [Connecticut], and Eastport [Maine]). Under 

 stones, shore. 



4. G. natator S. I. Sm. 1873 G. n., (S. I. Smith in:) A. E. Verrill in: Eep. 

 U. S. Fish Comm., v. 1 p. 558 | 1893 G. locusta (part.), A. Della Valle in : F. Fl. Neapel,^ 

 V. 20 p. 760. 



Pleon segment 4 with median fascicles of spjnes, segments 5 and 6 

 with median and lateral fascicles. Side-plates 1 — 3, lower margin setose. 

 Pleon segments 2 and 3, postero-lateral angles acutely produced. Eyes large, 

 long, slightly reniform. Antenna 1 shorter than antenna 2, setose, many of 

 the setae plumose. Antenna 2 also setose, ultimate Joint of peduncle longer 

 than penultimate, flagellum about % length of peduncle. Gnathopofl 1 in 

 ö more slender than gnathopod 2, 6*^^ Joint oval, palm continuous with 

 bind margin, defined by 2 small spines, with stout spine in middle of laminar 

 margin, finger strongly curved. Gnathopod 2, 6*^ Joint subrectangular, palm 

 slightly oblique, armed as in gnathopod 1, but with notch for the stout spine» 

 In 9 gnathopods 1 and 2 have 6*^ Joint smaller and slenderer, somewhat oval, 



