THE CANCROID CRABS OF AMERICA 279 



roughened on upper half; last three articles covered with short, 

 bristly hairs. 



Color. — Reddish brown (Nicolet). 



Measurements. — Male (21993), total length of carapace 33, width of 

 same 50, fronto-orbital width 18, width of front 10 mm. 



iJaugre.— Ecuador to Chile. Island of Juan Fernandez (Porter). 



Material examined. — 



PERU. — R. E. Coker, for the Peruvian Government: Bay of 

 Sechura, west of Matacaballa, in trawl at about 5 fathoms, April 8, 

 1907, 1 very young (40421). La Punta, tide pool on shingle beach, 

 December, 1906, 1 j^oung male (40422), 1 male (Peruvian Govern- 

 ment). 



CHILE.— Antofogasta; November 15, 1926; W. L. Schmitt; 1 

 male (60739). Santiago (?); 1 male (17537). Port Otway; Febru- 

 ary 10, 1888; Albatross; 8 males, 5 females (21993). Exact locality 

 not given; 1 immature female (Mus. Paulista, 1306). 



Variation. — The young have a more deeply areolated carapace, the 

 three dentiform lateral lobes more prominent and more acute, the 

 margin of the frontal lobes concave but not lobulated. 



Genus PLATYXANTHUS A. Milne Edwards 



Platyxanthus A. Milne Edwards, Ann. Sci. Nat., ser. 4, vol. 20, 1863, p. 280; 

 type, P. orbignyi (Milne Edwards and Lucas). 



Antero-lateral margins strongly arched; front very little advanced 

 beyond the arch, and deeply separated from the dentiform superior 

 angles of the orbits. Surface convex, uneven. Antero-lateral margin 

 cut into five teeth or lobes (including the orbital angle), some or all 

 of which are subdivided. Front typically quadridentate. Inner 

 lower tooth of orbit well developed. Basal article of antenna falls 

 far short of front. Anterior margin of merus of outer maxillipeds 

 oblique. Chelipeds unequal, strong. No subterminal tooth on merus 

 of ambulatory legs. Abdomen of male with its seven segments 

 distinct. 



South American coasts. 



KEY TO THE SPECIES OF THE GENUS PLATYXANTHUS 



A^ Merus of outer maxilliped longer than broad. 



B'. Second, third and fourth antero-lateral lobes deeply subdivided into 

 large teeth. Outer tooth of front directed forward. Fingers shorter 



than middle length of palm orbignyi, p. 280. 



B2. Antero-lateral lobes not deeply subdivided. Outer tooth of front di- 

 rected obliquely outward. Fingers as long as middle length of palm. 



cokeri, p. 283. 

 A^. Merus of outer maxilliped as broad as long. 



B'. Regions slightly indicated. Frontal lobes each subdivided by a deep 

 sinus into two tuberculiform teeth. Dark color almost covering 

 dactylus of chelipeds crenulatus, p. 281. 



