NATICIDA. 205 
they hide under the surface and burrow after bivalves. Range, 
from low-water to 90 fathoms. The colored markings of the 
shells are very indestructible, being frequently preserved on 
fossils. 
STIGMAULAX, Moérch. Whorls cancellated or sillonated ; umbil- 
icus with spiral funiculum. Operculum with calcareous outer 
layer. N. cancellata, Lam. (1xiii, 43). 
LUNATIA, Gray. (Huspira, Agass.,in part. Globularia, Swn.) 
Shell usually sombre-colored, covered with a dark, thin epider- 
mis; not so thick as the typical group; umbilicus open, without 
funiculum. Operculum corneous. Inhabit usually cold or tem- 
perate rather than tropical seas. N. heros, Say (xiii, 44). 
NEVERITA, Risso. (Naticaria, H. and A. Adams.) Shell 
depressed, orbicular, spire conical or flattened ; columella partly 
filled by a tongue-shaped callous process (funiculum) from the 
columella. Operculum horny. Animal capable of entire retrac- 
tion within the shell. Inhabits mostly temperate seas. WN. 
duplicata, Say (1xiii, 45). 
ANOMPHALA, Jonas. (Cernina, Gray. Bulbus, Brown.) 
Globular , imperforate, the columella with teas callous deposit. 
The animal is bulky, and unable to retract itself entirely into its 
shell. Operculum, if present, quite rudimentary. JV. fluctuata, 
Sowb. (Ixiii, 46). 
AMPULLINA, Lam. (Globularia, H. and A. Adams. Ampul- 
linopsis, Conr. Euspira, Agass., in part.) Umbilicus narrow 
(rimate), lined by a thin eallus. Operculum with calcareous 
layer. WN. Sigaretina, Lam. (1xiv, 66). 
MAMILLA, Schum., 1817. (Ruma, H. and A. Adams. Nati- 
earia, Swn.) Shell oval-conic, rather thin, with pointed spire ; 
whorls fasciated; mouth oblong, inner lip narrow, reflected. 
usually brown or black; umbilicus not funiculated. Oper- 
culum cartilaginous, oblong, narrower than the aperture. 
Animal capable of retraction “within its shell. N. maura, Lam. 
(xiii, 47). 
MAMMA, Klein. (Polinices, Montf. Naticella, Guild.) Shell 
oval or suboval, solid, smooth, spire short, sharp; aperture 
semicircular, inner lip oblique, callous, the callus extending into 
the umbilicus. Operculum corneous; animal retractile. WN. 
straminea, Recluz (lxiii, 48). The shell of Mamma is usually 
white, sometimes colored, but not banded or spotted. 
AMAURA, Moller. (Acrybia, H.and A. Adams. Ptychostoma, 
Laube.) Shell oval, smooth, imperforate, spire elevated, aperture 
oblong, columella short, simple. Operculum corneous, thin. The 
animal has a small , compact foot, without posterior lobe, anterior 
lobe profoundly sinuous, eyes at the internal base of the lobe. 
A boreal group, comprising a few living species. Fossil; Jurassic, 
Cretaceous, Tertiary. N. candida, Miller (Ixiii, 46). 
