AURICULID. 97 
Leruconta, Gray, 1840. 
Distr.—i sp. Europe, United States, West Indies, Loo Choo 
Islands. Fossil. Miocene of Europe. JZ. Sayi, Kuster (cii, 90). 
Shell oval-oblong, thin, nearly smooth, imperforate; spire 
conic; aperture oval-elongated ; columellar wall with one or two 
plaits ; columella with a distinct basal plait, oblique; peristome 
simple, without teeth. 
The Leuconias live in situations often covered by the tides. 
The animal has a foot truncated in front, obtuse behind, and 
transversely divided on the sole. The shell closely resembles 
Alexia. 
BiauneEriA, Shuttleworth, 1854. 
Distr.—3 sp. New Caledonia, Sandwich Islands, Europe, 
West Indies and United States. B. pellucida, Pfr. (cii, 91). 
Sheli sinistral, imperforate, oblong-turreted, thin; aperture 
narrow, elongated; inner lip with a single plait, columella sub- 
truncate ; outer lip simple. 
sToLipoMA, Deshayes, 1864. (Macrodonta, Desh.) Shell 
oblong, turriculated, subcylindrical; apex obtuse, smooth, 
polished; aperture elongated, obliquely inflected, narrowed 
behind, widened in front; columella straight, with a large 
median plait, compressed, and slightly oblique. 3 sp. Eocene; 
Paris Basin. #B. crassidens, Desh. (cii, 72). 
The shells of this genus are Auricule, with a single columellar 
plait, without teeth or plications on the right lip. 
Pepipes, Adanson, 1757. 
Distr.—l1 sp. Red Sea, Mauritius, W. Africa, New Cale- 
donia, Panama, Lower California. Fossil. Eocene; Paris Basin. 
P. afer, Gmel. (cii, 92). 
Shell imperforate, oval-subglobose, solid, spirally striate, 
whorls few, the last very large; aperture much contracted by 
teeth; columellar lip with usually three dentiform plications, 
of which the posterior one is largest and spiral; outer lip sharp, 
callous or dentate within. 
Foot divided inferiorly by a transverse groove. When the 
Pedipes walks, the hinder part of the foot is fixed, and the fore- 
part, which is separated from the hind-part by an extensible 
groove, is advanced, and the hind-half is then drawn forwards 
so as to touch the anterior half, and so progression is effected 
by a series of little steps. This movement, similar to that of the 
geometric or looping caterpillars, is executed with such quickness 
that few mollusks, according to Adanson, excel the Pedipes in 
alertness. The animal lives in tropical countries, in cavities of 
rocks, more especially of those exposed to the sea, 
