THE GBAPSOID CRABS OP AMEBICA. 263 



This species while closely related to C. angulatus, which inhabits 

 the same region, is much smoother and less ornate so that there is 

 no likelihood of their being confused. 



The carapace is not strongly areolated though the regions are well 

 defined; the gastric region lacks the beaded transverse ridge charac- 

 teristic of the older species. The surface is densely covered with 

 fine depressed granules and somewhat less numerous punctae; it 

 appears almost smooth to the naked eye, while in angulatus the 

 surface is obviously roughened with coarser granules. As to shape, 

 the carapace has no sharp lateral angles, the antero-lateral margins 

 are shorter than in angulatus, and the postero-lateral margins are 

 longer and subparallel to each other. The antero-lateral margins 

 have four teeth, including the orbital tooth, but they are small, 

 especially the last two, and do not project beyond the marginal line; 

 the intervals between the teeth diminish successively in length. 

 There is no indication of a postero-lateral tooth. 



The front is relatively wider than in angulatus and is feebly emar- 

 ginate at the middle ; the orbits are correspondingly smaller. 



The outer maxillipeds have much the same shape in the two spe- 

 cies, but in altimanus they are shorter and wider and the gape 

 narrower. 



The palms in the adult male are much higher in our species, espe- 

 cially at the distal end, and the movable finger is strongly deflexed ; 

 the immovable finger is nearly horizontal ; there is a triangular space 

 between the fingers for their proximal half only. 



Legs narrower than in angulatus, second and third pairs subequal ; 

 propodal joint and proximal part of terminal joint of first three 

 pairs fringed with hair on the posterior margin ; last two joints and 

 distal part of carpal joint of last pair fringed with hair on both 

 margins. 



The abdomen of the male is narrower and more oblong than in 

 angulatus, and the appendages of the first segment slenderer. 



Measurements. Male holotype, length of carapace 16.8, width of 

 same 18.4 mm. 



Range. Rio Grande do Sul, Brazil, and San Matias Bay, Pata- 

 gonia. 



Material examined. 



Rio Grande do Sul, Brazil; Capt. George Harrington; 1 male 

 (6127, M. C. Z.) ; received from Essex Inst., in exchange. 



San Matias Bay, Patagonia; Ilassler Exped.; male holotype 

 (6126, M. C. Z.) ; 2 males, paratypes (22835, U.S.N.M.). 



