REPOET ON THE BRACHYURA. 
253 
1. Grapsini. 
Grapsinx, Dana, tom. cit., p. 331. 
Exterior maxillipedes without an oblique piliferous crest on the ischial and meral 
joints. 
2. Sesarmi n i. 
Sesarminx , Dana, torn, cit., p. 333. 
Merus and ischium of the exterior maxillipedes crossed obliquely by a piliferous ridge. 
Nautilograpsus , Milne Edwards. 
Nautilograpsus, Milne Edwards, Hist. Nat. Crust., vol. ii. p. 89, 1837; Ann. d. Sci. Nat., 
ser. 3, Zool. xx. p. 173, 1853. 
„ Kingsley, Proc. Acad. Nat. Sci. Philad., p. 201, 1880. 
Planes (Leach, MS.), Bowdich, Excursion to Madeira and Porto Santo, p. 15, fig. 2, 1825 
(description insufficient). 
Carapace subquadrate, with the postero-lateral margins somewhat convergent, 
dorsally smooth and slightly convex, and usually with a slightly indicated lateral post- 
orbital tooth. The front is broad, usually about half the width of the carapace; its 
anterior margin projecting slightly and nearly straight. The orbits are small, and the 
margins entire or with only a very small notch beneath the eye-peduncles, near the 
exterior orbital tooth. The epistoma is short and broadly transverse. The longitudinal 
ridges of the endostome are distinct and well-defined. The post-abdomen in the male is 
distinctly seven-jointed, and its basal segments occupy the whole width of the sternum, 
between the coxae of the ambulatory legs. The eye-peduncles are short and thick. The 
antennules are transversely plicated. The basal joint of the antennae is short and 
robust, and is produced at its antero-external angle, which forms a lobe or tooth, and lies 
within the interior hiatus of the orbit ; the flagellum is short. The exterior maxillipedes 
have a rhomboidal gape ; the merus-joints are clistally truncated, and their anterior 
margins are even slightly concave ; the carpal joints are articulated near the rounded 
antero-external angles of the merus-joints. The chelipedes (in the adult males) are rather 
robust, subequal, of moderate size ; the merus-joints trigonous, and the anterior margins 
dentated ; carpi with a tooth or spine on the interior margins, palms somewhat turgid, 
rounded above ; fingers dentated on the interior margins and distally acute. The 
ambulatory legs are short, with the joints compressed, and (the merus-joints especially) 
somewhat dilated; the penultimate joints are ciliated on the superior margins, and the 
inferior margins are spinuliferous ; dactyli short, compressed and spinuliferous. 
Nautilograpsus is allied in some particulars to Trapezia in the Cancroidea, and to 
Litocheira, Kinahan, in the Carcinoplacidse, from both of which it is distinguished by 
the broader basal antennal joint and the compressed and robust ambulatory legs. 
