DESCRIPTIONS OF NEW SPECIES OF AMERICAN FRESH-WATER 



CRABS. 



Mary J. Rathbun. 

 (With Plates lxxiii-lxxvii.) 



Family PSEUDOTHELPHUSID^. 



PSEUDOTHELPHUSA Saussuie. 



The synonymy of this Ameiicau genus with a complete list of spe 

 cies is given by Prof. S. I. Smith in the Transactions of the Connecti- 

 cut Academy, Vol. ii, 1870. In the Annals and Magazine ot Natural 

 History (6) in, p. 7, 1889, Mr. E. I. Pocock describes a new species (P. 

 tenuipes) from Dominica, and gives distinguishing characteristics of all 

 the species. The collection of the United States National Musenia con- 

 tains no described species of Pseudothelphusa, but the genus is repre- 

 sented by eight new species. They all possess a cervical suture, two 

 epigastric lobes separated by a median suture, two small Y-sti'iped 

 depressions near the posterior margin of the gastric region, and five 

 rows of spines on the dactyls of the ambulatory legs, three rows above 

 and two below. The exognath of the external maxillipeds is shorter 

 than the ischium of the endognath. The species are grouped according 

 to the character of the front. 



A'. Front uot vertically deflexed, but rounding smoothly downward to the inferior ' 



margin. 



Pseudothelphusa jouyi. 

 (PI. Lxxiii; PI. Lxxiv, Figs. 1-3.) 



Carapace convex, punctate, smooth, and shining, much broader in 

 the male than in the female. Cervical suture short and curved, some- 

 times not continued to the antero-lateral margin. Epigastric lobes 

 faintly indicated by a short horizontal groove in front of them, of a 

 lighter color; sometimes the groove is obsolete, but the color remains. 

 There is no trace of a superior frontal crest, the front rounding smoothly 

 down to the margin, which is not visible from above and is strongly 

 retreating at the center. Median sulcus shallow, dividing the front 



Proceedings National Museinu, Vol. XVI— Xo. 959. 



649 



