THE GRAPSOID CRABS OF AMERICA. 241 



Lower border of orbit notched near its outer end. Orbital hiatus 

 partly filled by a lobe belonging to the inner fossa, which does not, 

 however, exclude the antenna from the orbit. Antennules almost 

 transverse. 



Epistome well defined, short fore and aft. Buccal cavity square 

 with the anterior corners rounded off. Maxillipeds having a rhom- 

 boidal gap between them; merus shorter than ischium, and bearing 

 the coarse palpus on its anterior border, nearer the outer than the 

 inner angle. 



Chelipeds either subequal or unequal, much more massive than the 

 legs. Fingers slightly grooved inside, forming shallow spoons at 

 the tip. 



Legs broad and compressed, especially as to the merus, which, 

 like the arm of the chelipeds, is transversely striated; the last three 

 joints have bristly edges and the dactyli are thorny. 



The abdomen in both sexes has seven segments, and in the male 

 covers the sternum at its base. 



Inhabits the Pacific and Atlantic coasts of America, the eastern 

 Atlantic, thence eastward through the Mediterranean to the Indo- 

 Pacific. 



KEY TO THE AMERICAN SPECIES OF THE CENUS PACHYGHAPSUS. 



A 1 . Carapace with one or two side teeth behind the outer orbital tooth. 

 B l . Carapace with one side tooth. 



C 1 . Distal end of posterior margin of merus of last pair of legs entire. 



D 1 . Sides of carapace strongly sinuous crassipes, p. 241. 



D*. Sides of carapace slightly sinuous maurus, p. 244. 



C*. Distal end of posterior margin of merus of last pair of legs dentate. 



D 1 . Edge of front sinuous transverstis, p. 244. 



D*. Edge of front simply convex gradlis, p. 249. 



B*. Carapace with two side teeth. 



C 1 . Striae of carapace naked marmoratus, p. 250. 



C J . Striae of carapace hidden by short hairs pubescens, p. 252. 



A*. Carapace without side teeth corrugatus, p. 252. 



ANALOGOUS SPECIES ON OPPOSITE SIDES OF THE CONTINENT. 



Atlantic. Pacific. 



maurus. crassipes. 



marmoratus. pubcscens. 



Species on both sides of the continent: transversus. 



PACHYGRAPSUS CRASSIPES Randall. 



Plate 59. 



Pachygrapsus crassipes RANDALL, Journ. Acad. Nat. Sci. Philadelphia, vol. 8, 

 1839 (1840), p. 127 (type-locality, Sandwich Islands; this locality is 

 probably erroneous; type in Mus. Phila. Acad. Nat. Sci.). DE MAN, 

 Notes Leyden Mus., vol. 12, 1890, p. 86, pi. 5, fig. 11. 



Grapsus eydouxi MILNE EDWARDS, Ann. Sci. Nat., ser. 3, Zool., vol. 20, 1853, 

 p. 170 [136], (type-locality, Chili; type in Paris Mus.). 



Leptograpsus gonagrus MILNE EDWARDS, Ann. Sci. Nat., ser. 3, Zool., vol. 20, 



1853, p. 173 [139], (Patrie inconnue; type in Paris Mus.). 

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