90 



Eriphia squamata Stimp., Annals Lye. Nat. Hist., N. Y., vol. vii, p. 

 56, 1859, and p. 217, 1860. Collected at Corinto, Nicaragua. 



Arenceus bidens, sp. nov. Male. Carapax granulous and naked 

 above, except between the teeth of the antero-lateral margin and 

 along the postero-lateral margin, where it is pubescent ; gastric re- 

 gion and the posterior part of the branchial, more convex than in A. 

 cribrarius. Front with two prominent, slender, obtuse, median teeth 

 separated from each other by a deep and narrow sinus, and from the 

 inner angles of the orbits, by broad rounded sinuses. Orbit broken 

 above by two fissures, which are deeper than in A. cribrarius, and the 

 truncated tooth between them more slender. Teeth of the antero- 

 lateral border long and subcylindrical, the anterior ones obtuse, and 

 the posterior ones acutely pointed; the one next the lateral spine 

 hooked forward at the tip, and longer than the one in front of it; the 

 lateral spine slender, nearly straight, and almost or quite as long as 

 the space occupied by the four teeth in front of it. Iufero-lateral re- 

 gions clothed with a long and dense pubescence. External maxilli- 

 peds, chelipeds, and ambulatory legs very much as in A. cribrarius; the 

 hands, however, are a little stouter, the teeth on the prehensile edges 

 of the fingers more slender and acute, and the spine on the outside of 

 the carpus is almost obsolete. Sternum flat posteriorly, and the 

 whole surface naked, minutely granulous, and sparsely punctate. 

 Terminal segment of the abdomen long and narrow, being twice as 

 long as broad, the extremity slender and acute. First pair of abdom- 

 inal appendages slender, reaching to the tip of the abdomen, curving 

 inward near the base, then gently outward to beyond the middle, and 

 then inward again to near the very slender tips, which are straight. 



The female differs very little from the male, but is somewhat thicker 

 and more convex, and the abdomen is broadly triangular as in A. crib- 

 rarius. 



In coloration, alcoholic specimens resemble A. cribrarius, but the 

 reticulations seem to be finer and more irregular. 



Several specimens give the following measurements : — 



Sex. 



Length of Cara- 

 pax including 

 frontal teeth. 



Breadth of Cara- 

 pax including lat- 

 eral spines. 



Ratio of 

 length to 

 breadth. 



Length of 

 lateral spine. 





mm. 



mm. 



mrtfT 



mm. 



Male 



24.4 



60.0 



1: 2.09 



9.8 



Male 



19.3 



48.0 



1 : 2.48 



7.0 



Male 



15.9 



41.4 



1 : 2.60 





Female 



15.3 



38.3 



1 : 2.50 





Collected at Corinto, Nicaragua, in June and July, 1868. 



