64 Couthouy's New Species of Mollusca 
4 
NucurLA TENUISULCATA. 
Plate III. fig. 8. 
N. testa elongatà, inzquilaterali ; latere antico longiore, attenuato; 
rostrato, postico rotundato; umbonibus prominulis, concentricé con- 
fertimque striatis, tenuism iique sulcatis ; colore virescente. 
Long. fifteen twentieths, lat. four twentieths, alt. seven 
twentieths, of an inch. 
Hab. waters of Mass. Bay. 
My own Cabinet. 
Cabinet of Bost. Soc. Nat. History. 
* of A. A. Gould, M. D. 
Description. Shell elongated, slightly convex, very 
inequilateral, anterior portion attenuated, rostrated, a 
little truncated and gaping at its extremity, nearly twice 
the length of the posterior portion, which is symmetri- 
cally rounded; closely covered with fine, concentric 
strie and sulci, running parallel to the base ; summits 
rather prominent, anterior dorsal area or lunule, lanceo- 
late, well impressed, and carinated in the middle; su- 
perior anterior margin a little depressed or coarctated, so 
as to form two, light carinations extending from the 
beaks to the extremity ; inferior or basal margin regu- 
larly rounded and entire; teeth 27 or 98, aculeated 
and very slightly recurvate; ligamentary fossa just be- 
fore the summits, small, inclined anteriorly, angular 
at its superior and rounded in its inferior portions ; 
ligament wholly internal; interior a pure brilliant white 
inclining to nacre; an elevated ridge extends from the 
beaks to the oval extremity, corresponding to the exter- 
nal depression : muscular impressions nearly impercepti- 
ble: epidermis an uniform sap green color, or light olive. 
