DESCEIPTI0:N"!S of two new species of FRESH-WATER 

 CRABS FROM COSTA RICA. 



By Mary J. Rathbun, 



Second Assistant Curator. Department of Marine Invertebrates. 



The Museo IsTacional de Costa Rica has recently sent, through Mr. J. 

 Fid, Tristan, a number of crabs and shrimps to the United States 

 Ilfatioual Museum for identification. Among them were found two 

 new species of Pscudothelphusa. 



PSEUDOTHBLPHUSA MAGlSiA, new species. 

 (Plates XXIX; XXX, iigs. 7-10.) 



Closely allied to P. richmotidi, Rathbun.^ Carapace wider than in 

 P. richmondi, branchial region more swollen, cervical suture sinuous. 

 The surface is covered with flattened granules, some of which on the 

 anterior half of the carapace are large and dark- 

 colored, looking like scales, but almost smooth to the 

 touch. The frontal lobes seen from above are sepa- 

 rated by a broad and deej) notch; margin uneven, 

 more advanced in its inner portion, passing gradually 

 into the orbital margin; the curve is much less abrupt 

 than in P. rk-hmondi. In Plate XXIX a portion of 

 tlie maxilliped shows beneath the front. The front 

 seen from before is much wider and less deep than in 

 l\ richmondi and the outer margins more oblique 

 (Plate XXX, figs. and 7). The external angle of 

 the orbit is nearly as advanced as the front, while in 

 /'. richmondi it is much less so. The spines or spinules 

 of the lateral margin are proportionally smaller than 

 ill P. richmondi. The eyes also are much smaller than 

 in P. richmondi and do not fill one-half the depth of the orbit. The 

 first abdominal appendage of the male is similar in character to that of 

 P. richmondi. It has three teeth at the extremity on the upper side. 

 (See npper left-hand portion of fig. 9.) The longitudinal plate on the 



Fig. 1. 



OUTER MAXILLIPED OF 

 PSEUDOTHELPHVSA 

 MAGNA. 



Natural size. 



I 



' Proc. U. S. Nat. Mus., XVI, 1893, p. 654, pi. lxxv, figs. 6-10. 

 Proceedings of the United States National Museum, Vol. XVIII— Xo. 1071. 



377 



