114 Notes on North American Orustacea, 



Pachygrapsus sociias, nov. sp. 



Closely allied to JP. transversus, but diiFering in several minor par- 

 ticulars. The carapax is somewhat narrower, less convex,- and more 

 strongly striated ; and the frontal region is more depressed and ex- 

 panded. The propodal finger of the chelipeds never has the dark 

 patch which is always more or less conspicuous in P. transversus and 

 P. inoiotatus. 



Dimensions of a male specimen : Length of carapax, 0.63 ; 

 breadth, 0.725 inch. 



There are 'specimens in the Smithsonian Collection from the 

 following localities : Peru, C. II. Raymond ; Panama, Alex. 

 Agassiz ; San Salvador, J. M. Dow ; Manzauillo, Mex., John 

 Xantus ; Cape St. Lucas, John Xantus. 



LEUCOSOIDEA. 

 Calappa coiivexa. 



Calappa convexn De Saussure, Rev. et Mag. de Zo6l., 1853, pi. xiii, fig. 3. 

 Calappa Xantudana Stimpson, Notes on N. American Crust., p. 109. 



There are specimens in the Smithsonian Collection from Cape 

 St. Lucas (Xantus), Mazatlan (BischofF), and Panama (Stern- 

 bergh). 



Osacliila acuta, nov. sp. 



Carapax depressed between the protuberances, and particularly 

 toward the antero -lateral margins, where it is broadly expanded and 

 concave. Protuberances rather small and somewhat conical ; the 

 three on the gastric region equal ; all of them tuberculated, and with 

 the tubercles coarsely punctate. Between the large protuberances 

 there are no small one.s, but the surface is smooth, naked, and micro- 

 scopically and crowdedly punctate. The rostrum is flattened, narrow, 

 prominent, and bilobed at the extremity; margin thin and shai-p, 

 and at the extremities of the lobes denticulated. Antero-lateral 

 margin acute, arciiated anteriorly but becoming nearly straight and 

 parallel to the axis of the body posteriorly; its armature is variable. 



