226 BULLETIN d1, UNITED STATES NATIONAL MUSEUM. 



F\ Antero-lateral margins dentate. Carapace convex. 



Sarmatium, p. 321. 

 F', Antero-lateral margins entire. Carapace posteriorly flat. 



Cyclograpsus, p. 325. 

 D'. Epistome projecting beyond the edge of the front. 



Chasmagnathus, p. 329. 

 C*. Antennae excluded from the orbit by the tooth at the lower inner 

 angle of the orbit meeting or nearly meeting the front. 

 D\ Dactyli of legs of ordinary length. Abdomen of male subtriangu- 



lar Metasesarma, p. 319. 



D'. Dactyli of legs very short. Abdomen of male subcircular. 



Aratus, p. 322. 

 A*. The antennules are visible in dorsal vievp in deep clefts in the front of 



the carapace Subfamily Plagnsiinae, p. 331. 



B\ Carapace broader than long Plagusia, p. 331. 



B*. Carapace longer than broad Percnon, p. 337. 



Subfamily Grapsinae Dana (part). 



Ch'apsavea Milke Edwards, Ann. Sci. Nat., ser. 3, Zool., vol. 20, 1853, p. 163 



[129] (part). 

 Grapsinae Dana, Amer. Journ. Sci., ser. 2, vol. 12, 1851, p. 287 ; U. S. Expl. 



Exped., vol. 13, Crust., pt. 1, 1852, p. 331 (part).— Alcock, Journ. Asiat. 



Soc. Bengal, vol. 69, 1900, pp. 288 and 295. 



Front usually strongly deflexed. The lower border of the orbit 

 runs downward toward the buccal cavern. Antennal flagellum very 

 short. The external maxillipeds leave usually a wide rhomboidal 

 gap between them, and are not traversed by an oblique hairy crest ; 

 the palp articulates at or near the antero-external angle of the merus, 

 and the exognath is narrow and exposed throughout. The m'ale 

 abdomen fills all the space between the last pair of legs. 



Genus GRAPSUS Lamarck. 



Grapsus Lamarck, Sys. Anim. sans Vert., 1801, p. 150; type, G. pictus 



Latreille=G. grapsus (Linnaeus). 

 Orthograpsus (part) Kingsley, Proc. Acad. Nat. Sci. Philadelphia, 1880. 



p. 194. 

 Goniopsis (part) de Haan, Fauna Japon., Crust, 1833, p. 5; 1835, p. 33. 



Carapace little broader than long, much depressed, regions fairly 

 well defined, branchial groove very clear, branchial regions with 

 regular obliquely transverse ridges, gastric region with transverse 

 squamiform sculpture. Lateral borders arched and armed with a 

 tooth just behind the acute outer orbital angle. 



Front about one-half the breadth of the anterior border of the 

 carapace, strongly deflexed ; along the line of flexion are 4 tubercles, 

 the outer of which form the supraorbital angles. 



Orbits of moderate size, deep, distinctly divided into two fossae; 

 lower border notched near outer angle ; the wide inner orbital hiatus 



