96 Proceedings of the Biological Society of Washi7igto7i. 



Description. — Carapace slightly convex, surface paved with flattened 

 granules among which are good-sized pnnctge visible to the naked eye ; 

 cervical suture sinuous and at its middle part deep; H -depression well 

 marked. Lateral margins roughened by small, blunt, irregular teeth; 

 two larger teeth are placed, one at the cervical suture, and the other, 

 obtusangled, a little behind the orbit. Front with a broad median V- 

 sinus above which separates two slightly sinuous and oblique lobes as 

 seen from above; from in front the lobes slope downward toward the 

 middle; the edge overhangs the surface of the front and is tuberculated, 

 the tubercles flat and not in a single row; the lower edge of the front is 

 deeply sinuous, three-lobed; surface of front deepest at outer ends, 

 although the middle lobe reaches a little lower down than the outer lobes. 

 Orbits in front view oblique, margins sub-rhomboidal. 



The orifice of the efferent branchial channel is almost closed, as the 

 antero-lateral angle of the buccal cavity is produced in a spine which 

 meets or nearly meets the lateral lobe of the epistome. 



Merus of outer maxilliped subtriangular, its outer margin concave or 

 nearly straight until near the distal end where it forms an angle or lobe 

 just behind the summit of the segment. Ischium widest a little behind 

 the distal end, the outer margin being sinuous. Exognath slender, about 

 % as long as ischium of endognath. 



Chelipeds noticeably unequal, roughened, the granules of the merus 

 fine and arranged more or less in transverse rugae ; inner margin armed 

 with triangular teeth increasing in size toward the distal end of the seg- 

 ment; surface of carpus, propodus and dactylus similar to that of carapace 

 but rougher; carpal tooth short, blunt; palm with lower edge swollen, 

 upper edge nearly straight ; fingers meeting when closed, and armed with 

 broad, low teeth. 



Abdomen of male with sides convex from the third segment to the 

 extremity; appendages of first segment armed distally with three lobes, 

 one stout at the external angle, two slender and overlapping at the 

 middle. 



Relationships. — This species in its shape is near P. colombiana Rath- 

 bun,* but differs in several important particulars: The shape of the 

 merus of the maxilliped is altogether different, in P. pearsei the outer 

 margin is straight, forming an angle with the anterior margin, while in 

 P. colombiana the outer margin is convex and curves into the anterior 

 margin. P. pearsei has two enlarged teeth on the antero-lateral margin, 

 while P. colombiana has in their places only slight interruptions in the 

 margin. The upper edge of the front is more horizontal, and the lower 

 edge less sinuous in P. colombiana than in P. pearsei. 



In my key to the species of the genus Pseudothelphusa,^ the species 

 pearsei would come directly after colombiana, on p. 275. 



Record of specimens. — Cincinnati Coffee Plantation, Santa Marta 

 Mountains, 4500 feet, under stone in brook, A. S. Pearse, July 2, 1913, 



• Proc. U. S. Nat. Mus., vol. 16, 1893, p. 653, pi. 74, fig. 10, pi. 75, fig. 1. 

 t Nouv. Arch. Mus. Hist. Nat., Paris, ser. 4, vol. 7, 1905, pp. 273-276. 



