382 CRUSTACEA [October 



by propelling the water to the natatory feet, by which it 

 was again propelled backwards; this constant stream car- 

 ries with it the more minute animals usually abundant in 

 sea water, which in passing are arrested by the plumose 

 antennae by the palpi and anterior feet, and are conveyed 

 to the mouth for food. 



Lepidactylis is related to the Gammarii by the acces- 

 sory seta of the intermediate antennae, but is generically 

 distinct by the form of the four anterior pairs of feet, and 

 that of the antennae, which combined have furnished the 

 essential characters for this genus. 



Genus AMFITKOE, Leach. 



Body of thirteen segments; antenna superior cs as long 

 or longer than the inferiores, four-jointed, seta of the pe- 

 nultimate joint obsolete, inferiores five-jointed; feet four- 

 teen, the two anterior pairs monodactyle, subequal; hands 

 equal, oval; third and fourth pairs smallest; tail destitute 

 of fasciculated spines, armed with bifid styles at tip, 



SPECIES. 



1. A. serrata^, jlntejina cqu2i\, short, stout; ez/c"^ large, 

 approximated, suboval; eighth, ninth, and tenth segments 

 of the body serrated. 



Inhabits Egg-harbour. 



Cabinet of the Academy. 



Clijpeus acute; antennae nearly equal, short, stout, at- 

 taining the base of the sixth segment of tlie body; eyes 

 large, black, oval, placed at the outer base of the superior 

 antenna, and approximated above; hands with about 

 three equidistant, prominent, spinose teeth on the inferior 



