122 



of the shell ; labium in the middle concave, with about two obso- 

 lete stria3, and a more profound one at base. 



Length seventeen-twentieths ; breadth nearly nine-twentieths of 

 an inch. 



In the collection of the Academy is a shell from the West 

 Indies, to which our species is very closely allied ; and although 

 the striae of the labrum are double in the former, yet it is probable 

 that the two shells will be found to constitute one species, when 

 more specimens are examined and carefully compared. In the 

 systems it will probably arrange near to iVi vnlgotum. 



For this shell I am indebted to Mr. Stephen Elliott, of Charles- 

 ton. 



Nassa alba. — Shell ovate, white, immaculate, longitudinally 

 ribbed or undulated, and with spiral striae ; ribs equal, equidistant, 

 symmetrical, from ten to eighteen on the body whorl ; strise equal, 

 equidistant, filiform, elevated as distinctly upon the ribs as in their 

 interstices, and from seventeen to twenty in number on the body 

 whorl ; whorls seven, convex ; suture deeply indented ; aperture 

 suborbicular ; labrum with a larger rib than the others on the ex- 

 terior, and striate within ; labium, plate distinct, entire, but not 

 expanded, with an indented line near the base, and a prominent one 

 near the junction with the labrum. 



Length nine-twentieths ; breadth three-tenths of an inch. 



Inhabits the southern coast of East Florida, and the West India 

 Islands. 



I owe this beautifully sculptured shell to the politeness of Mr. 

 Elliott. It seems to be more closely allied to N. macula of 

 authors than to any other wiih which I am acquainted. It is, 

 however, distinguished as a species by its more venVicose form, by 

 its ribs being more rectilinear, and by the spiral striae being more 

 prominent and distinct. Those found on the coast of Florida are 

 in no respect different from specimens brought from the West 

 India Islands. 



Nassa lunata. — Shell reddish-brown, with about six volu- 

 tions ; whorls with two revolving lines of dilated, sublunate, whitish 

 spots, and sometimes a third one at base ; suture not deeply im- 

 pressed ; labrum dentate on the inner submargin, the superior teeth 

 more prominent ; labium with the plate not thickened. 



