AN C ILL A. 



ber of fossil species that we are acquainted with, occur in 

 the Calcaire grossiere^ and in the London Clay ; we have 

 frequently seen one in a sort of Green sand^ from n^ar 

 Turin. 



The AncillcB are marine ; it did not at first occur to 

 us that they might be confounded with Lamarck's Mela- 

 nopsisj a fresh water Genus, as we know they have been, 

 particularly some of the fossil species ; this latter is, how- 

 ever, sufficiently distinct, and may be known by the tumid 

 upper part of its inner lip, and by the spiral line being 

 distinct, and not covered over with a shining enamel-like 

 coat ; when recent, moreover, the Melanopsis has a strong 

 blackish epidermis, and an horny operculum. 



Our Fig. 1. most nearly resembles Lamarck's Ancilla 

 ynarginata^ but it has not the " spira carinulatcC mentioned 

 by him in the character of that species. We believe Fig. 2. 

 is A, suhulata^ which differs from A. buccinoides^ in being 

 less gibbous. Fig. S. is probably A. glandiformis Lam. 



