164 S. I. Smith on American Crustacea. 



This species agrees perfectly with all the characters assigned to the 

 genus Euryplax by Stimpson, except in wanting wholly the pit on 

 the front side of the merus of the chelipeds. This character might, 

 perhaps, be considered generic, but, in the absence of any knowledge 

 in regard to its functional importance, it seems best to refer this spe- 

 cies to Euryplax, and especially, since it agrees so closely in most of 

 its specific characters with the type of that genus, 



G-lyptoplax, gen. nov. 



The carapax is cancroid in form and similar to Eucratopsis* The 

 dorsal surface is deeply areolated, the front is prominent and nearly 

 horizontal, and the antero-lateral margin is dentate and about as long 

 as the postero-lateral. 



The basis of the antenna is long and joins a slight process from the 

 side of the front. 



The epistome is much as in Panopeus. There is a sharp carina on 

 each side of the palate, along the efterent canal, but it is interrupted 

 a little way from the border of the epistome. 



The external maxillipeds are approximated along their inner mar- 

 gins. The ischium is longer than broad, and its anterior extremity 

 projects farther forward on the inside than the outside. The merus is 

 somewhat triangular, the antero-lateral angle is very prominent, the 

 anterior margin is very short and nearly parallel with the inner mar- 

 gin, which slopes oft* rapidly toward the antero-lateral angle. The 

 palpus is endarthroid. 



The chelipeds are short, but the hands are very stout. The ambu- 

 latory legs are slender and smooth. 



The seventh segment of the male sternum is exposed on each of the 

 abdomen. The verges pass from the coxje of the posterior legs to the 

 abdomen, through canals beneath the sternum. The sides of the first 

 segment of the abdomen extend in triangular projections to the coxaB 

 of the posterior legs; the second segment is much narrower than 

 either the first or the third ; the sides of the third segment do not 

 reach the margins of the sternum; and the third, fom-th, and fifth seg- 

 ments are anchylosed. 



This genus is allied to Eucratopsis, but differs very much from it in 

 the form of the external maxillipeds, in the more prominent and hori- 

 zontal front, and in the longer antero-lateral margins of the carapax. 

 From Speocarcinus Stimpson (Annals Lyceum Nat. Hist,, New York, 



* Eucrate Dana. See these Transactions, vol. ii, p. 35. 



