CALIFORNIA STALK-EYED CRUSTACEA. 79 



maxillipeds joined to the summit or autero-exterual angle of the merus. 

 Chelipeds in the adult male subequal and quite well developed; dactyls of 

 the ambulatory legs styliform, compressed, and armed with strong spines . 

 The base of the abdomen in the male usually covers the whole width of 

 the last thoracic sternum. 



The species, with rare exceptions, are littoral or 

 inhabitants of shallow water. 



Carapace striated. 



Orbits normal Pachygrapnus. 



Orbits bulged outward Grapsodius. 



Carapace not striated Brachynotus. 



Genus Pachygrapsus Randall. 



Carapace trapezoidal, depressed, and marked with transverse stride. 

 Front depressed and over one-half the width of the carapace. Inferior 

 subocular lobe small, not reaching the front, thus allowing the antennae to 

 enter the orbit. Eye-peduncles short and stout. Maxillipeds devoid of a 

 piliferous ridge and having a wide rhomboidal gap between them; merus 

 as broad as or broader than long, distally truncated and bearing the palp 

 at the summit. Chelipeds subequal, the merus trigonal, with the anterior 

 margin distally dentated. Legs of moderate length, merus dilated and 

 compressed, and furnished with an anterior subterminal tooth or spine; 

 dactyls more or less spinulous. Antero-lateral margins entire or with one 

 or two teeth. Abdomen in the male seven-jointed and covering the whole 

 width of the last thoracic sternum. 



Type. — P. crassipes Kaxdall. 



Pachygrapsus crassipes Randall. 



Pachygrapsus crassipes Randall, Journ. Acad. Nat. Sci. Phila., Vol. VIII, 

 1839, p. 127. H. Milne-Edwards, Ann. Sci. Nat. (3), T. XX, 1853, 

 p. 166. Stimpson, Journ. Bost. Soc. Nat. Hist., Vol. VI, 1857, p. 

 467. Lockington, Proc. Cal. Acad. Sci., Vol. VII, 1877, p. 153. 

 Streets, Bull. U. S. Nat. Mus., No. 7, 1877, p. 115. Kingsley, Proc. 

 Acad. Nat. Sci. Phila., 1880, p. 199. De Man, Notes Leyden Mus., 

 Vol. XII, 1890, p. 86, Tab. V, fig. 11. Ortmann, Zool. Jahrb. Abth. f. 

 Syst., Bd. VII, 1894, p. 707. Rathbun M., Proc. U. S. Nat. Mus., Vol. 

 XXI, 1898, p. 604. 



Carapace nearly square (the sides converging slightly posteriorly), 

 moderately convex, the entire upper surface, except the cardiac and intes- 

 tinal regions, transversely striated. The front is broad, depressed, slightly 



