III. — Notes on American" Crustacea. By Sidney I. Smith." 



No. I. OCYPODOIDEA. 



Read, December 15th, 1869. 



This article, which is intended as one of a series, is chiefly made up 

 of notes and descriptions resulting from the study of the higher Amer- 

 ican Crustacea in the Museum of Yale College and the collection of 

 the Peahocly Academy of Science. Mention is made only of those 

 species of which I have examined specimens and in regard to which 

 there are some new or unpublished facts to offer, except where men- 

 tion of such species seemed needful for the proper understanding of 

 new or imperfectly described forms. In the genus Gelasinius, I have 

 departed somewhat from this course and have given the principal 

 facts known to me, whether published or not, in regard to all the 

 American species. I have not attempted to arrange the groups ac- 

 cording to any zoological system, but have merely taken up the fami- 

 lies as convenience suggested. 



All specimens referred to, unless otherwise stated, are in the collec- 

 tions of the Museum of Yale College. 



Family, Ocypodid^. 

 G-elasimuS Latreille. 



The species of this genus, like most terrestrial crabs, seem to have 

 been neglected by collectors. This fact, together with the difticulty 

 of distinguishing the species from females or young specimens, and 

 the impossibility of determining, from the descriptions and figures 

 alone, what species many of the older authors had in view, has led to 

 much confusion in the synonymy. Even some of the modern authors 

 have published very imperfect desciiptions of numerous closely allied 

 species, neglecting to mention the form and ornamentation of the car- 

 apax or ambulatory legs, which give some of the best characters for 

 distinguishing the species. 



The genus, as at present constituted, is chiefly characterized by the 

 enormously unequal development of the chelipeds in the male. This 

 unsymmetrical development is not however confined to the chelipeds, 

 but extends to almost every part of the animal. The carapax, in every 

 species which I have examined, is more or less one-sided, the antei-o- 



Trans. Connecticut Acad., Vol. II. 8 March, 1870. 



