I^otes on North American Crustacea. Y3 



I'Eremite." Its dorsal integument is not indurated, but mem- 

 branaceous, and the animal consequently carries a valve of 

 some Venus or other bivalve, which serves it both for a pro- 

 tecting covering and a hiding-place. Guerin says that the 

 shell is held on by the posterior four feet, but the abdomen 

 seems to serve this purpose more fully, by being abruptly bent 

 and projecting near the middle, fitting firmly into the dorsal 

 or hinge-sinus of the shell. 



POKCELLANIDEA. 



Petroll§thes sex§pinosiis. 



Porcellana galatkina, Say ; Jour. Acad. Nat. Sci. i. 458 (vix Bosc). 



Gray ; Zool. Misc. 14. 

 Porcellana sexspinosa,*G[hhes ] loc. cit. 190. 



Found in considerable numbers on the Florida Keys, by 

 Wurdemann and Whitehurst. 



Petrolisthes occiclentalis, nov. sp. 



Scarcely to be distinguished from P. sexspinosus, but the 

 carapax is slightly broader, the spines less prominent and less 

 acute, and the abdomen and feet more pubescent. To esta- 

 blish these differences with certainty, however, the examination 

 of a large number of specimens is necessary. 



Found at Panama, by Messrs. Sternbergh and Rowell. 



Petrolisthes armatus. 



Porcellana armata^ Gibbes; loc. cit. 190. 



The outer edge of the hand in this species is generally 

 smooth, as the marginal spines mentioned by Gibbes, rarely 

 occur. 



