CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION I09 



ing in the young, and increases in size with age. This fact seems to 

 have been first noticed by Gerstsecker. The examination of numer- 

 ous specimens of all ages, taken in the harbor of Hongkong, enables 

 us to determine that the growth of the process may commence earlier 

 in some specimens than in others, but never before the body of the 

 individual reaches the length of two-thirds of an inch. So that 

 specific distinctions must rest mainly upon other characters, for a 

 difference in the length of the horn, even in specimens of the same 

 age or size, does not necessarily indicate specific diversity. 



It is probable that several spurious species have been founded 

 upon the different ages of O. ceratophthalma, to designate which, 

 however, an examination of the original specimens of the various 

 authors is necessary. 



The figures represent the appearance of the eye at different ages. 



This species in life is of a yellowish-white or light-gray color, 

 often finely punctate, and in the adult marked with two oblong brown 

 spots near the middle of the carapax. The parts about the mouth 

 are blotched with reddish-brown. Eye-peduncles brownish. Hands 

 white. There is sometimes a red spot on the third joint of the feet. 



It was found by us at Hongkong, Loo Choo, the Bonin Islands, 

 the Hawaiian Islands, and at Tahiti. It lives, like its congeners, in 

 holes in the beaches at and above high-water mark. 



171. OCYPODE CONVEXA Stimpson 

 Plate XV, Fig. 3 



Ocypodc convcxa Stimpson, Proc. Acad. Xat. Sci. Phila.. x, p. 100 [46], 

 " 1858. 



A. single specimen only, a female, of this species was taken, which 

 may be thus described : Carapax much swollen, posteriorly broad and 

 spreading over the bases of the feet. Proportion of length to breadth, 

 1 : 1.07. Surface nearly smooth, the granules with which it is cov- 

 ered being nnich flattened. Antcro-lateral angles prominent, acute ; 

 the margin immediately behind these angles straight or slightly con- 

 cave. Internal suborbital lobe slender, dentiform, bifurcated. 

 Infraorbital margin with a notch near the middle. Buccal area 

 large, with convex sides. External maxillipeds strongly protuber- 

 ant, not closely fitting to each other within ; their surface nearly 

 smooth, and more or less glossy; meros but little depressed at the 

 middle. Larger hand rather short and broad, dilated below ; fingers 

 much compressed ; outer surface depressed-granulated ; edges small 

 toothed. Fingers of the smaller hand compressed and produced. 



