12 BULLETIN 152, UNITED STATES NATIONAL MUSEUM 



lower border of the orbit. Outer maxilliped rather wide, ischium very 

 large; merus small, subtriangular, nearly as wide as long; palp very 

 short, inserted near summit of merus. Sternal plastron narrow, 

 oblong. Chelipeds large, compressed, of medium length. The four 

 pairs of legs are all nearly the same length, much compressed; dactylus 

 lamellate, broad and lanceolate, especially those of first and last 

 pairs. Abdomen very small and narrow-oblong; third, fourth, and 

 fifth segments fused. 



Contains but one species. 



PSEUDOCORYSTES SICARIUS (Poeppig) 



Plate 1, Figures 1-3 



Corystes sicarius Poeppig, Arch. f. Naturg., vol. 2, pt. 1, 1836, p. 139 (type- 

 locality, deep water opposite Bay of S. Vincent, Chili; type in Leipzig Mus.). 



Pseudocorystes armatus Milne Edwards, Hist. Nat. Crust., vol. 2, 1837, p. 151 

 (type-locality, Valparaiso; cotype in Paris Mus.; cotype. Cat. No. 20276, 

 U. S. Nat. Mus.). — Milne Edwards and Lucas, d'Orbigny's Voy. i'Amer. 

 Merid., vol 6, pt. 1, 1844, p. 30; atlas, vol. 9, 1847, pi. 15, figs. 2-2c. 



Pseudocorystes sicarius White, Cat. Crust. Brit. Mus., 1847, p. 53. — Rathbun, 

 Proc. U. S. Nat. Mus., vol. 38, 1910, p. 576.— Porter, Bol. Mus. Nac, 

 Chile, 1913, p. 359, text-fig. 2 and synonymy; Revista Chilena Hist. Nat., 

 vol. 22, 1918, p. 54, text-fig. 4 and synonymy. 



Corystoides armatus Philippi, Zool. Anz., vol. 17, 1894, p. 265. 



Diagnosis. — Carapace nearly as broad as long, granulate; sides 

 marginate, bidentate. Legs broad, natatory. 



Description. — Carapace convex antero-posteriorly as well as from 

 side to side; width about equal to length exclusive of rostrum. Two 

 shallow crescentic furrows near center of carapace. Surface rough 

 with crowded granules which are more acute and upstanding on the 

 anterior half. Rostrum triangular, tridentate, median tooth the 

 largest and most advanced. A sinus at middle of upper orbital border 

 followed by two large teeth on the anterior margin of the carapace, the 

 inner of which represents the external angle of the orbit. Two small 

 teeth on the antero-lateral margin, the posterior one rudimentary; 

 margin of teeth as well as of middle half of carapace thickly dentic- 

 ulate. Surface of chelipeds similar to that of carapace, granulation 

 coarser and sharper toward upper marg'n. Merus armed with a 

 small triangular spine near distal end of lower, outer margin; a strong 

 spine-tipped tooth at inner angle of carpus, a spinule on inner surface, 

 another smaller one on outer surface, sometimes absent; a denticle 

 near middle of low^er edge of propodus, and a series of spinules on 

 upper margin of dactylus and adjacent margin of palm. Fixed 

 finger triangular, broader at base than the dactylus. Fingers nearly 

 meeting, each with about 6 or 7 low prehensile teeth. Remaining 

 legs almost smooth, margins ciliated. Dactylus of last pair thinner 

 than the others, which are flat on the anterior surface and convex on 

 the posterior. 



