160 MOLLUSCA. GASTEROPODA. 



anterior canal and a posterior canal applied to the spire ; 

 outer lip expanded, thick or crenulate, with a notch in 

 front. Operculum small, oval or claw-shaped, edge not 

 serrated. Eocene to present day. 



Cypraea. Shell ovoid or elongate, convex, convolute, 

 surface covered with shining enamel. Spire concealed. 

 Aperture long and narrow, with a short canal at each end ; 

 outer lip, inflected and crenulated ; inner lip crenulated. 

 In the young forms the outer lip is thin and the spire 

 prominent. Cretaceous to present day. 



Buccinum. Shell oval or elongate, imperforate. 

 Spire long. Whorls ventricose, smooth or with longi- 

 tudinal folds. Aperture oval, large ; outer lip simple ; 

 anterior canal short, truncated, a little reflected. Oper- 

 culum small. Cretaceous to present day. 



Nassa. Shell ovate, ventricose, generally ornamented. 

 Aperture oval, with a short reflected anterior canal. Inner 

 lip callous, forming a tooth- like projection near the anterior 

 canal ; outer lip crenulate internally. Columella with an 

 oblique fold at its base. Cretaceous to present day. 



Purpura. Shell tuberculate, striated or lamellar, not 

 varicose. Spire short, last whorl large. Aperture oval, 

 large, with an oblique groove in front. Columella flattened, 

 callous. Operculum lamellar, nucleus external. Pliocene 

 to present day. 



Fusus. Shell imperforate, fusiform, elongate, spire 

 many-whorled. Aperture oval ; outer lip simple. A long 

 straight anterior canal, not closed. Columella smooth, 

 without folds. Operculum oval. Cretaceous to present 

 day. 



