THE GBAPSOID CRABS OF AMERICA. 21 



Off St. Lucia, 423 fathoms (A. M. E.). 



South of Pernambuco, lat. 9 5' to 10' S. ; long. 34 49' to 53' W., 

 between 300 and 400 fathoms (Miers). 



Genus PILUMNOPLAX Stimpson. 



Pttumnoplax STIMPSON, Proc. Acad. Nat. Sci. Philadelphia, vol. 10, 1858, p. 

 93 ; type, P. sulcatifrons Stimpson. ALCOCK, Journ. Asiat. Soc. Bengal, 

 vol. 69, 1900, p. 311. 



Carapace hexagonal, more or less depressed, a little broader than 

 long, regions often faintly indicated. Fronto-orbital border two- 

 thirds, or more, the greatest breadth of the carapace; the toothed 

 antero-lateral borders are slightly arched or oblique. 



Front straight, rather prominent, more or less confluent with the 

 supra-orbital angles, often notched or grooved in the middle line. 

 Supra-orbital border often with two fissures. The antennal flagel- 

 lum, which is of good length, stands in the orbital hiatus. The anten- 

 nules fold transversely or nearly so. 



Buccal cavity widening a little anteriorly, almost closed by the 

 maxillipeds. 



Chelipeds more massive than the legs, which are slender, their 

 dactyli compressed. 



Abdomen in the female and commonly in the male seven- jointed; 

 in the male the third segment covers the whole width of the sternum. 



Tropical and South Atlantic (deep sea), Arabian Sea (deep), 

 Japan, Hawaiian Islands, Fiji. 



KEY TO THE AMEI1ICAN SPECIES OF THE GENUS PILUMXOPLAX. 



A 1 . Carapace flat, regions scarcely indicated. No segments of male abdomen 

 fused americana, p. 21. 



A*. Carapace convex in an antero-posterior direction, regions defined. Third, 

 fourth, and fifth segments of male abdomen fused data, p. 23. 



PILUMNOPLAX AMERICANA Rathbnn. 



Pilumnoplax americanus RATHBUN, Bull. Lab. Nat. Hist. State Univ. Iowa, 

 vol. 4, 1898, p. 283, pi. 7, figs. 1 and 2 (type-locality, off Georgia, 440 

 fathoms; male holotype, Cat. No. 19G52, U.S.N.M.). 



Pilumnoplax sinclairi ALCOCK and ANDERSON, Ann. Mag. Nat. Hist., ser. 7, 

 vol. 3, 1899, p. 11 (type-locality, Travancore coast, 430 fathoms; type in 

 Indian Mus.). ALCOCK, Deep-Sea Brachyura Investigator, 1899, p. 74, 

 pi. 3, figs. 1-la. 



Pilumnoplax americana ALCOCK, Deep-Sea Brachyura Investigator, 1899, 

 p. 82 ; Journ. Asiat. Soc. Bengal, vol. G9, 1900, p. 311. 



Diagnosis. Carapace flat, regions scarcely indicated; edge of 

 front bimarginate. Wrist armed with 2 teeth. Segments of male 

 abdomen free. 



Description. Carapace a little more than three-fourths as long as 

 broad, very finely granulate, naked, regions fairly indicated. Front 



