Notes on North American Crustacea. 01 



portion of length to breadth, 1 : 1'65. Antero-lateral margin less than 

 half as long as the postero-lateral, and armed with three strong teeth, 

 including the angle of the orbit. Postero-lateral margin somewhat 

 concave. Front deeply notched on each side at the insertions of the 

 antennaj; the inter-antennal margin straight and smooth, with no me- 

 dian emargination. Chelipeds robust, smooth and glossy above ; meros 

 excavated at summit, with a small sharp tooth just behind the excava- 

 tion ; carpus flattened above, and unidentate within ; superior margin 

 of hand almost acute ; fingers somewhat deflexed. Inner side of carpus, 

 and surface of meros around the circular pit, densely pilose. Ambula- 

 tory feet slender, those of the third pair longest. Dimensions of the 

 carapax in a male : length, 0'65 ; breadth, 1*07 inch. 



Found on the Florida Keys. Museum of the Smithsonian 

 Institution. 



The most remarkable peculiarity of the crab above described, • 

 consists in the existence of a circular depression at the anterior 

 apex of the meros, concealed in the angle of the arm when 

 retracted. This I at first considered to be accidental, or the 

 work of some parasite ; but finding it in both chelipeds, with 

 exactly the same appearance and position, I am led to believe 

 it to be a prominent and important character, perhaps structu- 

 ral, although it is difficult to say what office it fills in the eco- 

 nomy of the animal. The aperture of the pit in our species is 

 one-twentieth of an inch in diameter, but the cavity expands 

 beneath the margin, which is ciliated ; the depth is about half 

 the diameter. The bottom of the pit is hard and crustaceous 

 like the rest of the surface. 



Ocypode Cc^tidichaudii. 



Ocypode Gaudickaudii, M.-Edw. et Lucas ; in D'Orbigny's Voy. en 



Am. Merid., Crust., p. 26 ; pi. xi. 



Found at Panama by Mr. Sternbergh. 



