542 



MOLLUSCA 



PHYLUM VI 



Hipponix Defr. (Gochlole'pas Klein) (Fig. 939). Shell thick, obliquely conical to 

 cup-shaped. Beak straight, rarely spiral, greatly removed pos- 

 teriorly. Aperture oval or rounded, internally with a horseshoe- 

 shaped muscular impression. The foot often secretes a thick, 

 operculiform calcareous disk. Cretaceous to Recent. 



93'J. 



Hipponix cornucopiae (Lamarck.) Calcaire 

 Grossier; Liancourt, near Paris. A, Shell. 

 B, Foot-plate. 



Fio. 940. 



Calyptraea {Trocli itn) trochiformis Lam. Calcaire Grossier ; 

 Damery, near Epernay. 



Galyptraea Lam. {Galerus Gray) (Fig. 940). Shell thin, conical, with central 

 spiral apex. Whorls flattened, often spinose. Base horizontal ; 

 aperture wide, depressed. Cretaceous to Recent. 



Crqndula Lam. (Fig. 941). Slijjper - shaped, elongate - oval, flat 

 or arclied. Beak at the posterior end, almost marginal, somewhat 

 curved. Aperture greatly elongated, wide ; inner lip formed by a 

 thin horizontal lamella. Cretaceous to Recent. 



Crucibuhtm Schum. Tertiary and Recent. 



Family 5. Naticidae Forbes. 



Fio. 941. Shell tuith short spire and large body whorl. Aperture semicircular 



Crepidula unjui- to oval, angular posteriorly, broadly rounded anteriorly. Operculum 



Trias to Recent. 



cen'et Tifscany. '°" calcareous or horny, paucispiral. Marine. 



The distinction of fossil Naticidae from Naticopsis, Nerita and Ampidlaria is 

 attended with some difficulty, since they frequently possess nearly identical characters 

 in common, difl'ering mainly in the operculum, which is not j^reserved fossil. 



Sinum Bolten {Sigaretus Lam.) (Fig. 942). Shell depressed, auriform, spirally 



Fic. 942. 



Sinum haHotoideum 

 (Linn.). Miocene ; Grund, 

 Hungary. 



A, Nat'tra milhpunctata Lam. 

 Pliocene ; Monte Mario, near Home. 

 B, (Jpercnlum of N. mnUipiitictata 

 S. Woodw. Crag; Sutton. 



Fii;. 944. 



Natica (Ampullina) palnia 

 Lam. Calcaire Grossier ; 

 Damery, near Epernay. 



striated or furrowed. Spire very low, with rapidly widening whorls. Aperture greatly 

 distended ; operculum horny. Tertiary and Recent. 



Natica Scopoli (Figs. 943-946). Globose, semi-globose, ovate or pyramidal, smooth 

 and lustrous, rarely spirally striated, umbilicate or not. The umbilicus, when 



