100 Rathbun Three New Mangrove Crabs from Costa Rica. 



Sesarma (Holometopus) biolleyi sp. MOV. 



Type. Male, in alcohol. Salinas de Caldera, Boca del Jesus Maria, Jan 

 uary, 1906. J. Fid. Tristan and P. Biolley, collectors. Cat. No. 32,490, U. S. 

 National Museum. 



Characters. Carapace a little broader than long, and broader behind 

 than before, very uneven, granulate anteriorly, punctate and wrinkled 

 posteriorly, nearly naked. Front J width of carapace, vertical, widening 

 below, lower edge projecting, convex in front view. Superior lobes well 

 marked, the middle pair wider. Upper margin of orbit sinuous, very 

 oblique, outer tooth acuminate. 



Chelipeds rugose, the rugse changing to single granules or tubercles on 

 the distal half of the palms ; the latter much inflated, inner face sparingly 

 granulous, a transverse row of granules near the distal end. Dactyli very 

 broad at base viewed from above and granulous. Legs long and narrow, 

 third pair 2\ times as long as carapace, its merus 3 times as long as wide. 



Measurements. Length, 19.1 ; anterior width, 20.2 ; posterior width, 21 ; 

 width of front above, 11.3 mm. 



Remarks. Allied to S. (H.) miersii Rathbun,* but differs in its carapace 

 narrower anteriorly, upper border of orbit inclined more strongly back 

 ward, front wider, and ambulatory legs much longer and narrower. Oc 

 curred in abundance at the type locality. 



Eurytium tristani sp. nov. 



Type. Male, in alcohol. Boca del Jesus Maria, hidden in the fine mud 

 of rotten trees. J. Fid. Tristan and P. Biolley, collectors. Cat. No. 32,366, 

 U. S. National Museum. 



Characters. Carapace slightly convex from side to side, strongly convex 

 from front to back. Gastric region with its subdivisions and cardiac 

 region well delimited. Surface finely granulate, without transverse striae. 

 Front ] as wide as carapace, bilobed, each lobe con vex except for an incon 

 spicuous outer tooth. Two distinct notches in the upper border of the 

 orbit ; tooth at outer angle blunt, prominent, and partly fused with the 

 next or second lateral tooth which is nearly as advanced as the first and 

 slightly larger ; third, fourth and fifth teeth prominent, with convex outer 

 margins ; anterior border of third tooth straight and transverse, of fourth 

 and fifth teeth concave and directed outwai'd and backward. Lower teeth 

 of orbit strongly'projecting. Merus of outer maxilliped not dilated at outer 

 angle. Chelipeds and legs as in E. limosum (Say), f 



Measurements. Length, 18 ; width, 28.2 mm. 



Color. Traces of violet on upper surface of chelipeds and of red on upper 

 surface of movable finger. 



Remarks. This species resembles E. limosum in its convexity but differs 

 in the cut of the front and antero-lateral teeth ; E. affme (Streets and 

 Kingsley) J is a much flatter species with inconspicuous side teeth. 



*Proc. Biol. Soc. Wash., XI, p. 91, 1897. 



t Jour. Acad. Nat. Sci. Phila., I, p. 446, 1817. 



f Bull. Essex Inst., IX, p. 106, 1877. 



