NO. 1158. 



FRESH-WATER CRABS OF AMERICA— RATHBUN. 



625 



inclined downward toward each other in a front view. Margins of 

 .orbits similar to those of dilatata, in that the upper and lower margins 

 are nearly strai.uht and parallel; just below the outer sinus, however, 

 the margin is produced in a shallow obtuse tooth in addition to the 

 regular crenulation of the margin. The last two segments of the abdo- 

 men of the male (fig. 15, d) are rather long, and their margins partly 

 concave. The appendages of the first segment (fig. 15, e',/) are more 

 like those of richmondi than any other species; distally tbey are much 

 compressed in a vertical direction, and on the upper margin have three 

 teeth, the anterior of which is on the inner side of the appendage, the 

 two posterior on the outer side; the posterior of these teeth is large, 

 acute, directed upward and backward; on the outer surface near 

 the extremity there is a small slender spine directed outward. The 

 outer maxillipeds (fig. 15, b) are wider than in any other described 

 species; the ischium of the cndognath much wider at its distal than 

 its proximal end; outer margin of the 

 merus with a very convex arch. 



Chelipeds very unequal. The larger 

 propodus (fig. 15, (•) is very deep; upper 

 margin slightly convex, lower margin 

 convex, forming a single curve to the end 

 of the pollex; fingers slightly gaping; 

 teeth very irregular; the largest tooth 

 occurs at about the middle of the pollex 

 in both chelipeds; in the greater one, 

 this tooth is strongly developed and out- 

 wardly protuberant, an effect probably 

 due to injury. The upper margin of the 

 smaller hand is slightly convex; lower 

 margin convex proximally, concave dis- 

 tally. The inner surface of the hands and fingers shows numerous 

 scabrous tubercles or granules, especially on the margins; these are 

 present, though much less distinct, on the outer surface. 



Dimensions.— M?de : Length, 37.5 mm. ; width, 59 mm. ; widtli of front 

 on lower margin, 14.2 mm.; depth of front, 1.7 mm. 



Type.—^o. 10-181, U.S.N.M.; one male. Tuxtla, Vera Cruz, Mexico, 

 1,000 feet elevation; E. W. Nelson and E. A. Goldman, May 16, 1894, 

 Biological Survey, U. S. Department of Agriculture. 



PSEUDOTHELPHUSA CONVEXA, new species. 



Superior margin of front Jceeled; carapace very convex longitudinally; 

 lateral outline of fourth to sixth segments of abdomen of male not arcuate 

 (fig. 16, d); appendages of the first segment similar to those ofV. tristani; 

 exognath reaching distal third of ischium of eiidognath. 



This species resembles P. refiexifrons and P. agassizii in being very 

 convex anteroposteriorly. Carapace smooth, excej^t along the postero- 



FlG. 15. — PSEUDOTHELPHUSA MAXIL- 



LiPES, MALE. a. Front, X 5. 6. Max- 

 iLLiPED, X IJ. c. Larger chela, x^. 

 d. Abdomen, x f. e. Right ahdomi- 



NAL APPENDAGE, OUTER VIEW, X 1§ 

 /. Left AUDOMINAL APPENDAGE, LOWER 

 VIEW, X \%. 



