164 



CRUSTACEA. 



315 



Pisa (Leach). Carapace triangular, rounded 

 behind, with a double stout beak, the two portions 

 of which diverge from the middle; a strong tri- 

 angular spine over each eye ; second joint of outer 

 antennae slender ; claws large in the male. 



P. tetraodon. Fig. 316 ; J n. s. 

 Gibbsii. 



