NATURAL SCIENCES OF PHILADELPHIA. 131 



NOTICE OF SOME CRUSTACEA FROM THE ISLAND OF ST. MARTIN, W. I., 

 COLLECTED BY DR. VAN RIJGERSMA. 



BY T. HALE STREETS, U.S.N. 



BRACHYURA. 



MAIOIDEA. 

 Pericera corktjta, H. Milne-Edwards. Hist. Nat. des Crust., Vol. I. p. 

 335 ; PI. XIV. bis. Fig. 5. 



OCYPODOIDEA. 



Gelasimus affinis, Nov. sp. 



Male. This species is very closely allied to G. mordax, Smith. 

 The carapax is convex longitudinally and slightly so transverse^. 

 The dorsal surface of the carapax is very similar to that of G. 

 mordax. Like that species it is punctate, and the space between 

 the puncta is perfectly smooth. The regions are but faintly 

 marked out on the dorsum ; a prominent sulcus separates the gas- 

 tric and cardiac regions. The front is broad and deflexed. Its 

 dorsal surface is grooved in the medial line ; the tip is curved back- 

 ward and downward so as to be completely hidden when looked 

 at from above ; it is bifid. The front is marginate above at the 

 point where it is curved backward. The upper edge of the supe- 

 rior orbital border is straight, but directed a little backward. The 

 ascent of the outer portion of the curved lower edge is much more 

 gradual and is longer than the inner portion of the same edge, 

 which is curved rapidly downward. The raised margin of the 

 lower edge is finely denticulated. The antero-lateral angle is some- 

 what projecting, and the anterior portion of the lateral border is 

 thin and straight. The margin is raised, and in some cases finely 

 denticulated. The posterior portion of it is curved inward and 

 terminates opposite the cardiac region. From the point where 

 the postero-lateral border turns inward, a line runs downward and 

 backward in a curved manner to join the posterior border. In the 

 space left by the divergence of these two lines there is one, and in 

 some cases two, short plications. 



In the larger cheliped, the merus is triangular in form, the ante- 

 rior surface is smooth, the borders are granular or tuberculose, 

 and the superior surface is arcuate and crossed by short pecteni- 



