NEW-YORK FAUNA CRUSTACEA. 



GENUS MITHRAX. Leach. 



Shield moderately convex above, longer than broad, and more or less narrowed behind, usually 

 armed with spines. Rostrum short, bifid, and separated by an interval from the internal 

 canthus. Orbits usually armed with spines above and beneath. External antenna? not 

 concealed by the rostrum. Pincers enlarged towards the end, rounded and spoon-shaped. 



Obs. We have no type of this numerous genus on our coast, except the following, which 

 is cited by Mr. Say from Delaware bay, and which we think will be found on the coast of 

 this State. 



MlTHRAX HISPIDUS. 



Cancer hispidus. Herbst, pi. 18, fig. 100. 



Maia spinicincta. Lamarck, An. sans vert. Vol. 2, p. 415, Ed. Brux. 



Mithrax spinicinctus. Desm. Consid. sur les Crust, p. 150, pi. 23, fig. 1. 



Main id. Say, Journ. Acad. Nat. Sc. Vol. 1, p. 458. 



Mithrax hispidus. Edwards, Hist. Nat. des Crust. Vol. 1, p. 322. 



Description. Shield short, convex, with its surface and margin spinous. Rostrum not ex- 

 tending beyond the basal joint of the external antennae, which are furnished with but two 

 spines ; the third joint of these antennae considerably longer than the second. Upper border 

 of the hands smooth. Pincers with about twenty indentations on the margin, but with no tuft 

 of hairs in the cavity. A series of small points under the tarsus of the four posterior pairs of 

 feet. 



This species, of which a specimen exists in the Cabinet of the Academy of Natural Sciences 

 at Philadelphia, from Delaware bay, extends through the Caribbean sea to the coast of Brazil. 

 Its northernmost geographical range is not yet ascertained. 



(EXTRA LIMITAL.) 



Genus Xantho, Leach. Exterior antennae very short, inserted at the internal canthus of the eyes. 

 Hands trenchant or rounded. A hiatus below the external orbital angle. Shield wider than 

 long, arcuated in front, truncated behind. 

 X. mercenaria. (L. id. Say, Jour. Acad. Nat. Sc. Vol. 1, p. 448. Edwards, 1. c. p. 399.) The 

 anterior lateral borders of the shield with four obtuse teeth ; front with a slightly sinuous fissure. 

 Feet hairy. Color, maculated; fingers black at tip. Length, 3*25; diameter, 4-5. Charles- 

 ton, S. C. 



