no. 1654. AMPHIPODA FROM WEST NORTH AMERICA— HOLMES. 527 



pods very slender, with straight dactyls. Last three pairs of peraeo- 

 pods greatly elongated; basal joints narrow, dactyls long and straight. 

 Pleopods large. First two pairs of nropods with narrow attenuated 

 rami ; third pair with the rami broader and more flattened. Telson 

 long, narrow, and emarginate. 



Type. — G. natator, new species. 



I have placed this genus in the family Calliopiidae, although it 

 forms a somewhat aberrant member of that group. The peduncles 

 of the antennae and the palps of the maxillipeds are much more elon- 

 gated than in the other genera. The genus Ilaliragoides approaches 

 it in having small side plates and long slender peraeopods with very 

 narrow dactyls, but in other respects it is quite different. 



GRACILIPES NATATOR, new species. 



Antennae very slender, about as long as the body, and of subequal 

 length. Peduncle of first antenna 1 elongate, about half the length 



Fig. 32. — Gracilipes natator. 



of the body, the second joint nearly a half longer than the first and 

 over twice the length of the third; fiagellum about equal to the 

 peduncle, the elongate segments furnished with minute setae less than 

 half the diameter of the segments in length. Second antenme with 

 the peduncle exceeding that of the first, the last joint very slender 

 and somewhat longer than the fiagellum and markedly longer than 

 the preceding joint. Along the lower and outer side of the first 

 antennae, and to a greater extent along the upper side of the second 

 pair, are numerous cup-like organs resembling calceolae both on the 

 peduncles and the flagella. 



