120 CREITHIID^. 



Section EUMETA, Morch, 1868. 



Lateral and marginal teeth of the radula finely pectinate. C. 

 ARCTICA, Morch. Northern Seas. 



Subgenus L^OCOCHLIS, Dunker and Metzger, 1874. 



Shell sinistral, elongated, granose, canal twisted. L. GRANOSA, 

 Wood. Boreal Seas. 



The dentition of this species is as near that of Trichotropis a# 

 Cerithiopsis, and von Martens has put it in Trichotropidse ; but the 

 affinities of the shell appear to be Cerithid. 



Genus CERITELLA, Morris and Lycett, 1850. 



Shell small, smooth, with sharp spire and flattened whorls, the 

 last whorl large, ventricose ; aperture elongated, oblique, narrow, 

 terminating in a very short canal, slightly turned outwards, lip 

 thin, columella smooth, rounded, subreflected at the base. 



C. ACUTA, Morris and Lycett (Struct, and Syst. Conch., t. 60, f. 

 57). Jurassic. England. 



Section TUBIFER, Piette, 1856. 



Shell formed like Actceon, the last whorl cylindrical, large ; aper- 

 ture long, the lip thin, simple, descending as far anteriorly as the 

 canal ; canal long, thin, tube-like. 



C. NUDA, Piette. Jurassic. 



Costellifer, Meek, 1863, may probably be referred here. 



Section FIBULA, Piette, 1857. 



Shell elongated ; columella straight with a rudimentary umbilical 

 groove near the base ; outer lip notched at the suture ; base of 

 aperture with a slight canal, or rounded and entire, depending upon 

 its age. 



C. UNDULOSA, Piette (Struct, and Syst. Conch., t. 60, f. 56). 21 

 sp. Jurassic to Cretaceous ; Europe, India. 



Genus EUSTOMA, Piette, 1855. 



Shell when young resembling Cerithitim ; in the adult there is a 

 long, narrow, nearly straight anterior canal, and an ascending 

 posterior channel, the lip is dilated, and there is a large spreading 

 columellar callosity. 



E. TUBERCULOSUM, Piette (PI. 19, fig. 7). Jurassic. 



Genus TRIFORIS, Deshayes, 1824. 

 Shell elongated, sinistral, granular ; whorls numerous ; aperture 



