PHERUSA BICUSPIS. 



253 



AMPHTPOBA. 

 NAT ATOM A. 



GAMMA RIDES. 



PHERUSA BICUSPIS. 



Specific character. First two segments of the pleon dorsally produced into 

 teeth, and the posterior margin of the third segment not serrated ; fourth 

 segment deeply sinuated. 



Length 2 5 inch. 



Amphithoe bicuspis. Kroyer, Grron. Amph. p. 45, pi. i. fig. 1. 

 Pherusa bicuspis. Milne Edwards, Hist, des Crust, t. iii. p. 38. Spence 



Bate, Cat. Amph. Brit. Mus. p. 144, pi. xxvii. 



fig. 7. 

 Pherusa cirrus. Spence Bate, Cat. Amph. Brit. Mus. p. 143, pi. xxvdi. 



fig. 6. 



The head is anteriorly produced between the supe- 

 rior antennae. The first two segments of the tail have 

 the dorsal surface posteriorly produced into sharp cusps 

 or flat teeth ; the third segment has the postero-lateral 

 margin smooth a circumstance which offers a ready 

 point of distinction between this species and Atylus 

 bispinosus. The eyes assume a little of the kidney- 



