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UNIVALVES. DENTALIUM. 



The D. miuutuni 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 tlie 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, 



DE^TALIVM.— Tooth-Shell. 



Ele^hantmwxi— Elephant's tooth 

 Aprinum — White-ribbed. 

 Arc uatu m — Curved. 

 Striatulum — Striated. 

 Sexangulum — Six-ribbed. 

 Dentalis — Slightly curved. 

 Fasciatum — Banded. 

 Rectum — Straight. 

 Fossile — Fossil. 

 Annulatum — Round. 

 Radula — Decussated. 



Interruptum — Interrupted stri^B 

 Politum — Polished. 

 Eburneum — Ivory Tusk. 

 ♦Entails — Dog's-tooth. 

 Arietinum — Ram' s-tooth. 

 Corneum — Horny. 

 Nebulosum — Clouded. 

 Pellucidum — Pellucid. 

 Vitroum — Glassy. 

 Minutum — Minute. 

 ♦Imperforatum — Imperforated. 



