TRTCHOTROnS. 279 



lateral curved, the inner one denticulated, the two outer 

 simple. Rostrum broad and short; tentacles wide apart, 

 bearing the eyes on bulgings at the extremities of their 

 lower halves. Mantle enclosed, with a rudimentary si- 

 phonal fold. Foot small, simple. 



Operculum subannular, ovate, horny, with a sublateral 

 nucleus. 



Shell spiral, more or less turbinate; whorls covered 

 with an epidermis ; aperture sub-eraarginate anteriorly ; 

 columella not plicate. 



In their dentition, these animals have a strong analogy 

 to Velutimdce and Naticidce, but the head of the animal 

 is furnished with a rostrum ; the foot is rather small and 

 simple, and the form of the shell varies considerably, 

 being either imperforate or widely umbilicate, smooth or 

 cancellated, turbinate or turreted. The species are 

 chiefly from the Northern Seas, where they inhabit deep 

 water ; a few, however, are from the warmer parts of the 

 globe, as T. Jlavidula and T. cancellata. 



Genus TRICHOTROPIS, Broderip and Sowerby. 



Shell turbinate, or somewhat elevated, thin, more or less 

 distinctly umbilicated, spirally furrowed or cancellated, 

 the ribs often furnished with epidermal fringes ; apex of 

 spire acute; aperture pyriform, angulated in front; colu- 

 mella obliquely truncated, canal rudimentary; inner lip 

 flattened, arcuated ; outer lip simple, acute. 



Syn. Trycophore, Desk. Trichotropus, Less. Tri- 

 chopodus. Sow. 



Ex. T. boreahs, Broderip and Sowerby, pi. 29, fig. 6. 



