NERITACEA. MOLLUSCA. NATICA. 237 



brighter, and the shell more smooth, as might be expected if modified 

 by a milder climate. A figure in Lister, (pi. 562, f. 3,) represents this 

 shell. 



Ndtica conica, of Lamarck, is a much more elevated shell, though 

 his description might be applied to our shell in every particular. 



Its ordinary length is half an inch less than is given above. 



Natica pusi'lla. 



Shell small, sub-oval, ash-colored ; umbilicus imperfect ; oper- 

 culum horny. 



Figure 166. 

 State Coll., No. 42. 



Natica pusilla, Say ; Journ. Acad. JVat. Sc, ii. 257. 



Shell sub-oval, bluish-white, with a light, ash-colored epider- 

 mis ; surface glossy, smooth, or with merely microscopic revolv- 

 ing lines, and lines of growth ; whorls four, regularly convex ; 

 spire moderately elevated, blunt ; suture fine and deep, the edge 

 of the whorl rising a little by the side of it ; sometimes one or 

 two faint, brownish bands may be seen on the lower whorl ; 

 apertiu-e ovate, more than half the length of the shell ; outer lip 

 thin and sharp ; inner margin thick, the callus white, abundant, 

 and pressed into the umbilicus so as to leave only a narrow, curved 

 chink by the side of the lip ; throat white ; operculum horny. 

 Length I inch, breadth | inch. 



Taken from fishes caught in Massachusetts Bay, in company 

 with N. clausa, and N. immaculala. 



Most of the specimens have about half the dimensions above given. 



I was not a little gratified in looking over a parcel of the N. clausa, 

 to find several specimens ditTering from them in having a horny in- 

 stead of a bony operculum, a partial umbilicus, and no flattening of 

 the top of the whorls. In color, size, and general aspect, they were the 

 same. On finding that this shell corresponds to Mr. Say's N. pusilla, 

 I was still more gratified, inasmuch as it is represented in the Cabinet 

 of the Academy of Natural Sciences, at Philadelphia, by a species of 

 Margarita {Tiirho infldtus, Totten), and I had despaired of finding 

 any representative elsewhere. Mr. Say remarks, that it is generally 

 mistaken for the young of N. duplicdfa. But the evidences of ma- 



