6 Proceedings of the Biological Society of Washington. 



seum. Collected in Rio Guiare, near Caracas, Venezuela, by Dr. Juan 

 Iturbe, August 4, 1918, and presented by him to the National Museum. 



Measurements. — Male holotype, length of carapace on median line 40 

 mm., width of carapace 64 mm., width between outer angles of orbits 

 36.7, width of front above, between the eyes, 18.4 mm., width of front 

 below 16.3 mm. 



Description. — Near P. garmani; 1 the upper edge of the front, between 

 the eyes, carinated and tuberculated, the outer margin of merus of maxil- 

 liped arcuate, and the exognath reduced to a stump. Differs from P. 

 garmani in several particulars : In the absence of a giant tubercle on outer 

 face of palm just between bases of fingers; upper edge of front in dorsal view 

 a little arcuate or sloping backward from the median emargination, this 

 edge, in garmani, being almost transverse; orbit in front view higher in 

 outer half than in garmani; abdomen of male wider. 



Potamocarcinus dunoonensis, sp. nov. 



Holotype. — Adult female, Cat. No. 53312, United States National 

 Museum. Collected at Dunoon, Demerara River, British Guiana, by E. N. 

 Clarke, August 27, 1915, and given to the National Museum by the Uni- 

 versity of Michigan. 



Measurements. — Female holotype, length of carapace on median line 

 47.8 mm., width of carapace 76 mm., width between outer angles of orbits 

 43 mm., width of front above, between the eyes, 20.1 mm., width of front 

 below 16.7 mm. 



Description. — Carapace very convex from front to back, much less so 

 from side to side. Cervical suture straight. Lateral teeth or spines small, 

 23 behind, 8 or 9 before, the cervical suture. Upper margin of front nearly 

 straight, median emargination broad and shallow, lobes sloping a little 

 backward outwardly and rough with from 14 to 16 irregular tubercles; 

 surface of front very uneven, inclined downward and backward; lower 

 edge quadrilobate. 



Maxillipeds very convex when closed, outer margins arcuate; merus 

 subtriangular; exognath one-third as long as outer margin of ischium. 



A conical sharp spine at inner angle of wrist; lower margin of larger 

 propodus convex. Merus of legs roughened above with elongate tubercles; 

 dactyli armed with slender spines. 



lProc. U. S. Nat. Mus., vol. 21, 1898, pp. 522, 534 and 537, text-fig. 14; Nouv. Arch. 

 Mus. Hist. Nat., Paris, vol. 7, 1905, p. 298, text-fig. 91. 



