322 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



Front more than half as wide as the whole anterior margin, its 

 free edge concave at middle as seen from above, straight as seen 

 from before. Antero-lateral margins of carapace distinctly arched 

 and cut into three blunt teeth including the orbital tooth, the last 

 tooth being much the smaller. 



Chelipcds of male stout, hand above with a tuberculate edge and 

 an obliquely longitudinal, pectinated ridge, outwardly a little rough- 

 ened; movable finger crossed above by transversely oblique rugose 

 ridges, and just outside these a longitudinal, milled ridge; carpus 

 covered with fine, irregular granulated lines. In the female the 

 fingers are nearly smooth. 



Legs thick; merus joints with a subdistal spine above; dactyli 

 stout, long-pointed, subequal to the propodal segments. 



Color. Violet. 



Measurements. Male (20309), length of carapace 23, width of 

 same 28.5, width of front 13.8 mm. 



Range. Martinique, West Indies; west coast of Africa. 



Material examined. 



Martinique; 1 male dried, type of M. pectinatus (Paris Mus.). 



Senegal; 1 male type (Paris Mus.). 



Congo; Dybowski coll.; 189G; 1 male, 1 female (20309) ; 9 speci- 

 mens (Paris Mus.). 



Remarks. The type-specimen of Metagrapsus pectinatus in the 

 Paris Museum has been compared with a typical specimen of 

 Sesarma curvata from Senegal. The crest on the hand of the latter 

 is less prominent than on the former, but the specimen is smaller. 



Genus ARATUS Milne Edwards. 



Aratns MILNE EDWARDS, Ann. Sci. Nat., ser. 3, Zool., vol. 20, 1853, p. 187 

 [153] ; type, A. pisonii (Milne Edwards). 



Very narrow behind. Antenna excluded from orbit. Abdomen 

 of male subcircular. 



Carapace trapezoidal, strongly narrowed behind. Front very 

 broad, vertical, reaching nearly to buccal cavity, concealing the an- 

 tennulae. Epistome very short, fore and aft. Antenna removed 

 from the orbit by the broad lobe at the inner suborbital angle. Outer 

 maxillipeds separated from each other by a small gap; merus oblong- 

 oval, distinctly longer than the ischium. Dactyli of legs short. Ab- 

 domen of male, save for the last segment, subcircular. Otherwise 

 much as in Sesarma. 



Contains only one species. 



