REPORT ON THE AMPHIPOD CRUSTACEANS. 



By S. I. Smith. 



Hyalella, geyius nov. 



First pair of maxilise with rudimentary, very short, and uniarticulate 

 palpi. Palpus of the maxillipeds (Fig. 5) composed of five segments, 

 the terminal segment being slender and styliform, and the penultimate 

 longer than broad. Autennulse, antennae, and thoracic legs much as in 

 Eyale. Telson short, stout, and entire. 



Hyalella dentata, s]^. nov. (Plate I, Figs. 3-6.) 



Body slightly compressed. First and second segments of the abdo- 

 men with the dorsal margin produced posteriorly into a well-marked 

 spiniform tooth. Eyes nearly round, about equal in diameter to the 

 thickness of the jjroximal segment of the peduncle of the autennula. 

 Peduncle of the antennula about as long as the head ; the ilagellum a 

 little longer than the peduncle, and composed of about seven to nine 

 segments. Antenna somewhat longer than the antennula 5 the two 

 distal segments of the peduncle elongated and nearly equal; the Ilagel- 

 lum usually but little longer than the flagellum of the antennula, and 

 composed of about eight to twelve segments. 



First pair of thoracic legs (Fig. 6) small and slender ; the palmary 

 margin of the propodus transverse, nearly straight, and armed with a 

 small tooth at the inferior posterior angle ; the dactylus very strongly 

 curved, and its tip closing behind the inferior posterior angle of the 

 propodus. Second pair of legs, in the male (Fig. 3, terminal portion), 

 very large; carpus projecting into a process along the posterior side of 

 the propodus ; propodus very stout, about as long as* the epimerou, and 

 a little longer than broad, its palmary margin strongly oblique, a little 

 arcuate, with an abrupt notch near the middle, and two slight emargi- 

 nations near the posterior inferior angle ; the dactylus stout and strongly 

 curved. In the young males, the palmary margin of the propodus of the 

 second pair of legs (Fig. 4) is less oblique, and the emarginations of 

 the edge nearly obsolete, and the dactylus is much less curved. In the 

 female, the second pair of legs is weak and slender, and the carpus 

 and hand elongated and narrow; the propodus not broader than the 

 merus, more than twice as long as broad, the posterior inferior angle 

 produced distally, so that the nearly straight prehensile portion of the 

 palmary margin forms less than a right angle with the posterior margin ; 

 the dactylus slightly curved and fitting closely the palmary margin. 

 Seventh pair of legs only slightly longer than the sixth, and with the 

 basis broad and its posterior margin serrate, as it is also in the fifth 

 and sixth pairs. 



The inferior posterior angles of the first three segments of the 

 abdomen a little less than right-angled, but not produced. First 

 pair of caudal stylets considerably longer than the second. Third 

 pair short, the basal segment not reaching by the basal segments of the 

 second pair, nearly as broad as long, and armed on the outside, at the 

 distal extremity, with three or four stout spines ; the terminal segment 



