GRAPSOIDEA. 351 



of second, third, or fourth pair of legs villous below, and in part 

 pubescent above. Fifth pair pubescent above and below, on fourth, 

 fifth, and last joints. Antero-lateral margin of carapax three-emar- 

 ginate, two posterior emarginations quite small. 



Plate 22, fig. 5 a, hand of male, natural size ; 6, leg of second pair, 

 ibid.; c, leg of fifth. pair, ibid.; d, part of outer maxilliped; e, abdo- 

 men and sternum. 



Rio Negro, Northern Patagonia. 

 Length of carapax, seven lines. 

 // affinis, DANA, Proc. Acad. Nat. Sci. Philad., 1851, v. 250. 



GENUS CYRTOGRAPSUS. 



Carapax fere octagonus, angulate gibbosus,fronte angusto, margine super 

 antennas internas prominenter reftexo, eoque his antennis valde obliquis 

 et non transversis. Maxillipedes externi rhombic!} hiantes, articulo 

 Stio subtriangitlafo, vix anyustiore quam longo. 



Carapax nearly octagonal, angulately gibbous, the part of the front 

 over the inner antennae reflexed, and these antennae, therefore, 

 nearly longitudinal, or very oblique instead of transverse. Outer 

 maxillipeds with a broad rhomboidal interval, third joint subtrian- 

 gular, hardly narrower than long. 



The" angular aspect of the species is peculiar, and especially the 

 front, which in a front view is very sinuous, the part over the inner 

 antennae being arched upward so as to afford space for the base of these 

 antennas in a nearly longitudinal position. The antero-lateral margin 

 is four-dentate ; from the last tooth a sharp ridge proceeds inward and 

 slightly backward. The anterior legs are stout in the male, and quite 

 small and weak in the female. The outer antennae have the first 

 joint very short and not reaching to the front, or nearly so, as in 

 Hemigrapsus; on the contrary, the first and second joints together reach 

 the front. The length of the front is not over a third of the breadth 

 of the carapax. 



