CRUSTACEA. 



to constitute the genus Heloecius. The most striking peculiarity of 

 the species of Gelasimus, as adopted, is the very great inequality of the 

 hands in males. In this character, and also the spatulate or spoon- 

 excavate character of the fingers of the smaller hand, and the very 

 slender eyes with short cornea, the species are very unlike those of 

 the genus Ocypoda. The Gelasimi, moreover, are marsh species, while 

 the Ocypoda are found about sand beaches. 



GELASIMUS NITIDUS. 



G. Duperreyi similis. Carapax nitidus, antice paulo arcuatus, fronte 

 angustissimo, supra paulo constricto. Pedes maris antici valde incequi, 

 manu majore valde compressd et laid, extus valde granulatd, intus 

 cristis duobus obliquis ornatd, digito superiore laminato, fere duplo 

 latiore quam inferior, inferiore juxta basin uni-dentigero. Pedes 8 

 postici fere nudi, articulo Ztio pedis quinti perangusto. 



Near the Duperreyi. Carapax shining, a little arcuate anteriorly, 

 front very narrow, and somewhat narrow constricted above. An- 

 terior feet of male very unequal, the larger hand much compressed 

 and broad, strongly granulous without, and having two oblique 

 crests within, one towards lower margin; upper finger laminate, 

 nearly twice as broad as lower, the lower with a prominent tooth 

 near base. Eight posterior feet nearly naked, the third joint of 

 fifth pair very narrow. 



Plate 19, fig. 5 a, male, natural size ; &, abdomen and sternum, 

 enlarged two diameters ; c, outer view of larger hand of male, natural 

 size ; d, inner view, showing the two crests, natural size. 



From the Feejee Islands. 



Length of carapax of a male, six and one-fourth lines; breadth 

 between anterior angles, nine lines; length of large hand, sixteen 

 lines ; length of moveable finger, nine lines ; and its greatest breadth, 

 three lines. The crests on the inner surface of the hand are made 

 up of largish granules; one is near the articulating side, and the 

 other towards the lower margin ; the lower finger terminates in two 



