6 NATlCIDjE. 



The species are numerous; mostly inhabitants of warm sens, 

 in all quarters of the globe. The genus first appeared in the 

 Jurassic formation. The fossil forms are remarkable for the 

 persistence of their colors. Nacca, Risso, is a synonym. 



Section STIGMAULAX, Morch, 1852. 



Whorls cancellated or grooved. N. cancellata, Lam. 



Subgenns NEVERITA, Risso, 1826. 



Shell large, depressed orbicular, spire conical or flattened ; 

 umbilicus open, or partly filled by a tongue-shaped callous process 

 (funiculum) of the columella. Operculum corneous. Dentition, 

 PI. 1, fig. 0. N. duplicate, , Say. 



The shell of Neverita is usually larger sized, sombre colored, 

 and not so solid as that of Natica. The group inhabits mostly 

 temperate waters. 



Section NEVERITA (typical). 



Umbilicus partly filled by a tongue-shaped callous process of 

 the columella. 



Section LUNATIA, Gray, 1847. 



Shell subglobose, large, umbilicus open, without funiculum. 

 Almost insensiblj r connects with Neverita. Operculum, PI. 1, 

 fig. 14. N. heroSj Say. 



Section PAYREAUDAUTIA, Bucquoy, Dautzenberg and Dollfus, 

 1883. 



Umbilicus furnished with two funicular plications; shell small, 

 variegated. N. intricata, Donovan. 



Appears to connect with the typical group which it resembles 

 in coloration, but distinguished by its umbilicus and operculum. 



Section MAMMA, Klein, 17f>3. 



Shell oval or suboval, solid, smooth, usually unicolored, white 

 or yellowish ; aperture semilunar, inner lip oblique, callous, the 

 callus extending into and more or less complete!}' filling the 

 umbilicus. N. uber, Yal. 



Polinices, Montf., 1810, Mamillaria, Swains.. 1840, Nali<-uui, 

 Guildintr, 1884, and Naticella, Guilding, 1840, arc- synonyms. 



Section CEP ATI A, Gray, 1840. 



Shell rotelliform ; umbilicus closed by a large callosity, a 

 pliciform lamella on the upper part of the columelhir lip. Fossil 

 only. N. cepacea, Lam. Eocene. 



