VOL. XIX, PP. 99-100 JULY 30, 1906 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



DESCRIPTIONS OF THREE NEW MANGROVE CRABS 

 FROM COSTA RICA. 



BY MARY J. RATHBUN. 



By permission of the Secretary of the Smithsonian Institution. 



Prof. .1. Fid. Tristan and Prof. P. Biolley of San Jose are 

 making a study of the fauna of the mangroves of Costa Rica, and 

 have submitted the crabs to me for examination. Three new 

 species have been discovered, the types of which have generously 

 been given to the U. S. National Museum. 



Sesarma (Sesarma) rhizophorae sp. nov. 



Type. Male, in alcohol. Boca del Jesus Maria, in the mud of mangroves, 

 January, 1906. J. Fid. Tristan and P. Biolley, collectors. Cat. No. 32,491, 

 U. S. National Museum. 



Characters. Carapace f as long as wide, short-pubescent, smooth, punc 

 tate, very convex longitudinally, less so transversely. Front more than % 

 width of carapace, steeply inclined, sides parallel, lower edge sinuous in 

 top view, convex in front view, superior lobes smooth, low, outer pair nar 

 rower than inner pair. Orbital margin directed strongly backward and 

 outward, with a curved tooth at outer angle, behind which on the lateral 

 margin there is a second strong tooth separated from the first by a deep 

 sinus. 



Arm and wrist crossed by short granulated rugae; palms coarsely punc 

 tate, upper margin a single line of granules, inner surface partly granu- 

 lous, some oblique lines near the top ; dactylus punctate at base and with 

 a granulate line above on the basal half. Legs pubescent, with some 

 longer hairs, third pair about 2] times as long as carapace; merus joints 

 armed with a slender subterminal spine ; dactyli having a long slender 

 tip ; merus of third pair about 2| times as long as wide. 



Abdomen of c? narrow except at its base ; appendages of first segment 

 ending in long needle-like points. 



Measurements. Length, 10.9 ; anterior width, 13 ; width at lateral tooth, 

 13.7 ; posterior width, 12.8 ; width of front, 7.5 mm. 



Remarks. This is the representative on the Pacific coast of S. curacao- 

 ense de Man*, in which, however, the legs are much shorter and broader, 

 meral spines shorter and stouter, abdomen of c? broader, appendages of 

 first segment stouter and devoid of slender tips. 

 * Notes Leyden Mus., XIV, p. 257, pi. X, fig. 6, 1892. 



23 PROC. BIOL. Soc. WASH., VOL. XIX, 1906. (99) 



( JUN 21 



