134 UNIVALVES. DENTALIUM. 



The D. miijutum inhabits the Mediterranean ; it is a 

 round, straightish, smooth shell, and so very minute as 

 scarcely to be discernible by the naked eye; it resembles 

 a small bristle, or one of the spines of an echinus. 



The D. imperforatum (from Sandwich and its neigh- 

 bourhood) is also a minute species, and is by no means 

 common. 



The fossil species of the Dentalia are the D. sexangulum, 

 and D. fossile? both from Loretto; and the D. annulatum, 

 D. radula, D. interruptum, and D. vitreum, from Piedmont. 



The recent species are mostly from the Indian and Eu- 

 ropean oceans ; though some few are from the Mediter- 

 ranean and Northern seas, and one species inhabits the 

 shores of Africa, 



VE^^TALIVM.— Tooth-Shell. 



Ele^haxitmxim— Elephant's tooth Interruptum — Interrupted stria: 



Aprinum — White-ribbed. Politum — Polished. 



Arcuatum — Curved. Eburneum — Ivory Tusk. 



Striatulum — Striated. *Entalis — Dog's-tooth. 



Sexangulum — Six-ribbed. Arietinum — Ram's-tooth. 



Dentalis — Slightly curved. Corneum — Horny. 



Fasciatum — Banded. Nebulosum — Clouded. 



Rectum — Straight. Pellucidum — Pellucid. 



Fossile — Fossil. Vitroum — Glassy. 



Annulatum — Bound. Minutum — Minute. 



Radula — Decussated. *Imperforatum — Imperforated. 



