208 NATICID^. • 



sea ; usually, however, they are found living on stones near low- 

 water. 



VELUTELLA, Gray. Shell thin, flexible, pellucid, smooth, mem- 

 branaceous ; spire somewhat elevated ; mouth oblong, columella 

 flexuous. V. Jlexilis, Mont. (Ixiy, 8Q). 



[ltmneria, H. and A. Adams. (Morvillia, Gray.) Shell semi- 

 globose, with wide expanded aperture, sometimes extending pos- 

 teriorly beyond the apex ; inner lip oblique, reflexed posteriorly, 

 straight and acute anteriorly. V. zonata, Gould (Ixiii, 64, 65), 

 which has been referred to the pulmoniferous genus Otina, is a 

 typical species.] 



LEPTONOTis, Conrad. Differs from Velutina in the remarkable 

 expansion of the outer lip, and the distance of the apex from 

 the margin. V. expansa, Whitfield (Ixiv, 68, 69). Eocene; 

 Alabama. 



AMPLOSTOMA, Stoliczka. Subovate, thin, spire short; whorls 

 few, the last large, ventricose, produced in front, widely exca- 

 vated at base ; aperture elongately ovate, subangulated, pillar- 

 lip smooth, outer lip dilated and expanded at the margin ; 

 surface nearly smooth. Cretaceous ; So. India, Europe. A. 

 auriforme, Stoliczka (Ixiv, 85). 



Platyostoma, Conrad. 



Distr. — P. Niagarensis^ Hall (Ixiv, ti). Niagara group. New 

 York. 



Shell subglobose ; spire short ; aperture very large, suborbic- 

 ular, dilated; labrum joining the body-whorl at right-angles to 

 the axis of the shell. 



STROPHOSTYLUS, Hall. Shell subglobose or ovoid-globose ; spire 

 small, with a large, ventricose body-whorl; outer lip thin, not 

 reflected (sometimes slightly expanded ) ; columella twisted or 

 spirally grooved within, not reflected ; umbilicus none ; aperture 

 somewhat round-ovate or transversely broad-oval. Fossil. Lower 

 Helderberg. ■ S. obtusus, Hall (Ixiv, 75). In this the columella 

 is said to be twisted or spirally grooved within, whilst in Platy- 

 ostoma the columellar lip is simply thickened. 



ORIOSTOMA, Mun.-Chal., 1876. "XJmbilicus moderate, circum- 

 scribed by a carina; whorls sometimes partially free. 0. Ba7'- 

 randei, Mun.-Chal. Devonian. 



[lysis, Gabb (p. 112), may perhaps be related to Velutina.] 



Lamellaria, Montagu. 



Etym. — Lamella^ a thin plate. 



Syn. (Larval form). — Brownia, d'Orb. {B. Candei, d'Orb., 

 Ixxxvii, 8, 9). Calcarella, Souleyet (0. spinosa, Soul., xx, 51). 

 Jasonilla, Macdonald. Echinospira, Krohn {JE. diaphana, Kr., 

 XX, 49, 50). 



