AURICULID^. 97 



Leuconia, Gray, 1840. 



Distr. — 7 sp. Europe, United States, West Indies, Loo Choo 

 Islands. Fossil. Miocene of Europe. L. Sayi, K'nster (on ^ 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. 



Blauneria, Shuttleworth, 1854. 



Distr. — 3 sp. New Caledonia, Sandwich Islands, Europe, 

 West Indies and United States. B. pellucida^ Pfr. (cii, 91). 



Shell sinistral, imperforate, oblong-turreted, thin ; aperture 

 narrow, elongated ; inner lip with a single plait, columella sub- 

 truncate ; outer lip simple. 



STOLiDOMA, Deshayes, 1864. (Macrodonta, Desh.) Shell 

 oblong, tnrriculated, 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 Auriculte, with a single columellar 

 plait, without teeth or plications on the right lip. 



Pedipes, Adanson, 1757. 



Distr. — 11 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 usuall^^ 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 bj^ 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. 



