azotes on North American Crustaeea. 189 



Mithrax hispidus M. Edw., Hist. Nat. des Crust., i. 322. 

 Gibbes, Proc. Am. Assoc. 1850, p. 1V2. 



Carapax naked, punctate, not granulated, broadly trian- 

 gular. Marginal spines tuberculiform, excepting the posterior 

 ones, which are spiuiform. Basal joint of the external antennae 

 narrower tlran in allied species, and armed with only two 

 spines, which are tuberculiform. Hands smooth above. 



Found at Key Biscayne, Fla., by Mr. Wurdemann, and at 

 the Tortugas by Capt. "Woodbury. 



ITIithrax tiiberculattis, nov. sp. 



Carapax naked, tuberculated ; tubercles more or less prominently 

 granulated, most so in the young. Margin armed on each side with a. 

 strong unguiform spine or tooth curved forward. Between this lateral 

 spine and the orbit, there are two large, well-rounded tubercles, whose 

 distance fi'om each other about equals their diameter ; the posterior one 

 is largest and most prominent. On each side of the lateral spine (before 

 and behind it) there is also a smaller marginal spine or sharj) tooth. 

 Front narrow ; horns of the rostrum short, blunt, scarcely more promi- 

 nent than the anterior tooth of the basal joint of the antennae. This 

 joint is triangular, narrowing before, and is armed on the under side of 

 the orbit with another, a lateral tooth, very small. A small tooth, 

 posterior to this, scarce belongs to the antennal joint. Pterygostomian 

 ridge or margin tuberculated. Meros-joint of the external maxillipeds 

 with a right-angled notch at the inner apex for the insertion of the 

 palpus. Chelipeds naked ; meros tuberculated ; carpus sparsely granu- 

 lated ; hand smooth ; fingers scarcely gaping, and unarmed within, ex- 

 cept that there is a tooth on the dactylus in old specimens. Ambula- 

 tory feet thick, subcylindrical, nearly naked, short-spinose or granulated 

 above, tomentose below. Dried specimens are cream-colored, mottled 

 with carmine. In old specimens the carmine predominates. In a large 

 male, the carapax measures 1.37 inch in length, and 1.67 in greatest 

 breadth. 



