ACADEMY OF SCIENCES. 



149 



entirely smooth, with a few hairs. Abdomen of male with all the joints dis- 

 tinct, gradually narrowing from the base. 



<? P 



M. M. M. M. 



Length of carapax 9 8.5 



Width of carapax 14 13 



Length of larger hand 19 



The larger hand greatly resembles that of the species I have referred to 

 G. brevifrons, but the fingers are proportionally shorter, a character which 

 may, however, be due to immaturity. The great differences between this 

 form and G. brevifrons are the entire want of the meral plications, and the 

 form of the lateral margins of the carapax, which in the latter continue 

 nearly perpendicular to the front for some distance before they commence to 

 converge. 



A single pair is all I have seen of this form. Tbe great convexity of the 

 carapax, and the absence of any coarse granules on the front and anterior 

 part of the branchial regions, distinguish it from G. panamensis. 



Gelasimus crenulatus. nov. sp. 



Carapax highly convex, transverse, antero-lateral angles acute and promi- 

 nent, slightly posterior to the front; superior orbital margin sinuous, inferior 

 crenulated, the teeth equal in size and with a straight upper edge. 



Dorsal surface smooth and shining; median and lateral gastric regions 

 clearly marked off; cardiac distinct; branchial regions prominent, tumid, 

 each divided in two by an indistinct sulcus, parallel with the lateral margins 

 of the carapax. 



A broad ridge on the inner edge of the fourth joint of outer maxillipeds, 

 continued downwards along the greater portion of the inner edge of the third 

 joint. Merus of greater cheliped stout, triquetral, marked with numerous 

 short, transverse, not prominent rugas. Carpus and manus smooth and un- 

 armed, except a few small tubercles on the raised line anterior to the de. 

 pression for the carpus on the inside of the manus. Propodal finger long 

 and slender, pointed at tip, and with a tubercle in the centre of its length. 

 Dactylus longer than propodal finger, curved, the tip of the curve consider- 

 ably overpassing that of the latter. Merus of smaller hand slender, tri- 

 quetral, smooth, carpus smooth, about equal in length to the palm of the 

 manus; fingers equal, parallel, near together, touching at tips, which are 

 pointed. 



Hands of female like those of smaller male cheliped. Ambulatory feet 

 smooth and shining, with a few long setas on the propodi, and more numer- 

 ous and shorter seta? on the dactyli. 



The hand of this species is similar to that of G. brevifrons; the gibbous 

 carapax, with its areolations, resembles closely G. gibbosus, but the third > 

 fourth and fifth segments of the abdomen are free, instead of anchylosed, as 

 in that species; and the margins of the carapax again resemble those of the 

 species I have referred to G. brevifrons, but the convexity of the surface, with 

 the tumid branchial regions, give it a very different appearance. 



