632 Bulletin American Museum of Natural History [Vol. XLVIII 



dactylus cut out in a deep sinus, into which projects a crenulated tooth of the im- 

 movable finger; both fingers irregularly dentate. 



The chelipeds of the female have both fingers horizontal and longer than the 

 immovable finger of the male; they do not gape, and the teeth fit rather closely 

 together. In the young male the chelae are intermediate in form between those of the 

 adult male and of the female, and the gape is lacking. 



Ambulatory legs with merus-joints rather short, (in the fourth pair 2% times as 

 wide as long), widening distally, and crossed by fine short rugae; dactyli slender, 

 longer than their respective propodi measured on the outer or anterior margin. 



Abdomen of male broadly triangular; terminal segment as broad as long. Ap- 

 pendages of first segment rather slender, tips oblique. 



Color. — Specimens preserved in alcohol have a greenish-blue carapace mottled 

 with purple; upper, proximal half of chelae reddish-brown; upper surface of legs 

 covered with a pattern of fine dots of dark purple on a light ground. 



This species is unlike other American Sesarmae in its faintly marked 

 frontal lobes, which give it much the appearance of a Metasesarma, e.g., 

 M. rousseauxi Milne Edwards 1 and M. aubryi (A. Milne Edwards). 2 In 

 Sesarma magdalenense, however, the inner orbital lobe, although large, 

 does not meet the angle of the front and exclude the antenna from the 

 orbit. 



GECARCINIDiE • 



Cardisoma crassum Smith 

 1870, Trans. Connecticut Acad. Arts and Sci., II, p. 144, PI. v. 

 Agua Verde Bay; 1 9 . 



OCYPODID.ffi 



Ocypode occidentalis Stimpson 

 1860, Ann. Lye. Nat. Hist. N. Y., VII, p. 229. 

 Cape St. Lucas; March 23; 3 cf. 

 Carmen Island: with 175-foot seine; Apiil 3; 3 c? 3 9 . April 7; 



2 cf . 



Uca crenulata (Lockington) 

 Gelasimus crenulatus Lockington, 1877, Proc. California Acad. Sci., VII, 1876, p. 

 149. 



Mangrove Island, Magdalena Bay; March 20, 1911; 4 cf. 



Agua Verde Bay; April 2; 1 cT. 



Head of Concepcion Bay; April 6; 13 cf. 



U853, Ann. Sci. Nat., Zool., (3) XX, p. 188 [154]. 



2 Sesarma (Holometopus) aubryi A. Milne Edwards, 1869, Nouv. Arch. Mus. Hist. Nat. Paris, V, 

 p. 29. 



