MUSEUM OF COMPARATIVE ZOOLOGY. 109 



No. 2. — Preliminary Report on the Crustacea dredged in the 

 Gulf Stream in the Straits of Florida, by L. F. de Pourtales, 

 Assist. U. S. Coast Survey. Part I. Bkachyura. Prepared 

 by Dr. William Stimpson. 



(Communicated bt the Superintendent of the TJ. S. Coast Survey.) 



The Crustacea collected by M. Pourtales are very numerous in 

 species, and among them there is an unusually large proportion of new- 

 forms ; so that their investigation has occupied more time than was 

 anticipated. To avoid delay in publishing a portion at least of the 

 results, it is thought best to give at once that part of the work which 

 has been done thus far, reserving the completion for a second part, in 

 which the general considerations derived from the entire study will also 

 be given. 



To preserve accuracy in the statements of localities and depths, and 

 to insure the correction of any errors which may have occurred, all the 

 details on the labels of each species are given below, arranged in the 

 order of depths of water. 



MAIOIDEA. 



Family MAIIDAE. 



Subfamily LEPTOPINAE. 



The group typified by the genus Leptopus Lamarck (Egeria Latr.) should 

 be separated from the Inachinae of Dana on account of the broad and 

 somewhat heart-shaped meros-joint of the external maxillipeds, which in 

 Inachus is simply ovate and elongated, with the palpus articulated at the 

 small extremity. 



Pyromaia nov. gen. 



Carapax somewhat pyriform, convex ; rostrum simple, slender, of moder- 

 ate length, acute ; transorbital breadth small ; prseorbital spine short, 

 almost erect; postorbital tooth rather large, pointing forwards. Meros- 

 joint of the external maxillipeds short and broad, deeply and broadly 

 notched for the reception of the palpus, and with the inner lobe strongly 

 projecting and the outer lobe angular. Ambulatory feet long ; those of 

 the first pair three times as long as the post-frontal portion of the carapax. 



This genus approaches nearest to Microrhynchus Bell, but differs in 

 its more elongated and pyriform carapax, larger rostrum, and prominent, 

 angular external lobe of the meros-joint of the outer maxillipeds. Prom 

 Leptopus it differs in its simple rostrum. 



