THE CANCROID CRABS OF AMERICA 425 



EURYTIUM TRISTANI Rathbun 



Plate 176, Figure 3; Plate 177, Figure 3 



Eurytium tristani Rathbun, Proc. Biol. Soc. Washington, vol. 19, 1906, p. 100 

 (type-locality, Boca del Jesus Maria, Costa Rica; type, Cat. No. 32366, 

 U. S. N. M.): Proc. U. S. Nat. Mus., vol. 38, 1910, p. 543, pi. 47, fig. 1. 



Diagnosis. — Carapace very convex, widest at tips of teeth of last 

 pair. Frontal lobes each with a slightly marked truncate outer 

 lobule. Sinus between coalesced teeth pronounced. 



Description. — Carapace widest between tips of lateral teeth of last 

 pair; slightly convex from side to side, strongly convex from front to 

 back, but less so than in E. limosum. Cardiac region and gastric 

 region and its subdivisions well delimited. Surface finely granulate. 

 Front one-fourth or, in the old, less than one-fourth as wide as carapace, 

 bilobed, each lobe convex except for a slightly marked transverse 

 outer tooth. Two distinct notches in upper border of orbit. Lateral 

 teeth more prominent, less shallow than in E. limosum; first tooth 

 blunt, partly fused with the second tooth, which is lobiform, nearly as 

 advanced as the first and usually larger; anterior margin of fourth 

 and fifth teeth concave; posterior margin of third, fourth and fifth 

 teeth convex; that of fifth tooth sloping backward and inward. 

 Lower teeth of orbit strongly projecting, the outer one a rounded lobe. 



Chelipeds and legs as in E. limosum. 



Color. — Upper surface of chelipeds violet, of movable finger red. 



Measurements. — Holotype male, length of carapace 18, width of 

 same 28.2, fronto-orbital width 15.5, width of front 7 mm. Male 

 (40418), length of carapace 34, width of same 51.6. 



Habitat. — All the specimens [in Costa Rica] were found in rotten 

 mangroves, hidden in fine mud. (Tristan.) 



Range. — From Costa Rica to Peru. 



Material examined. — 



COSTA RICA.— Punta Arenas; February, 1907; P. Biolley col- 

 lector; 1 female (39093), from J. Fid. Tristan. 



Boca del Jesus Maria; P. Biolley and J. Fid. Tristan collectors: 1 

 male, holotype (32366), from J. Fid. Tristan. January, 1906; 1 male 

 (32492), from Costa Rica National Museum. 



PANAMA. — Canal Zone; 1911; Smithsonian Biological Survey: 

 Corozal; April 20-21; 1 male (Field Mus.). Balboa; tide water; 

 May 5; 1 male (44183). 



PERU. — Salto (near Capon); January 31; R. E. Coker; 1 male 

 (40418), received from Peruvian Government; 1 female (Peru Govt.). 



EURYTIUM AFFINE (Streets and Kingsley) 



Plate 177, Figures 1 and 2 



Pano-peus transversus Lockington, Proc. California Acad. Sci., vol. 7, 1876 (1877), 

 p. 102; not P. transversus Stimpson, 1860 (San Bartolomd, Magdalena and 

 Santa Maria Bays, and La Paz, all in Lower California). 



