112 UNIVALVES DENTALIUM. 



time are encircled witli annular ones. The Dentalium 

 Fasciatum is a small species, finely striate, and is encircled 

 with four or five brown bands on a greyish ground. 



The next division of the Dentalia comprehends those 

 which are striate annularly instead of longitudinally, and 

 those which are scarcely striate at all, at least so imper- 

 ceptibly as to demand the aid of a glass to prove whether 

 they are in reality striate or perfectly smooth, so even 

 and polished is their surface. 



Those species which answer to this description are the 

 Dentalium Politum or Polished Tooth-shell, which is fine- 

 ly pointed, solid, and often of a rosy or pinkish color ; 

 the Dentalium Eburneum or Ivory Tusk, and the Den- 

 talium Entalis or Dogs'-tooth-Shell, which is an inhabi- 

 tant of the Indian and European shores, and is generally 

 an inch and a half long, of a reddish or pale yellow co- 

 lor, with the tip often tinted with orange or pink. The 

 Dentalium Pellucidum is of a horny or pale honey color, 

 very narrow and thin, and not effervescing with acids ; it 

 is an inhabitant of the North seas, and about two inches 

 and a quarter long. 



The Dentalium Minutum inhabits the Mediterranean, 

 it is a round, straightish, smooth shell, and so very minute 

 as scarcely to be discernible by the naked eye ; it resem- 

 bles a small bristle, or one of the spines of an Echinus. 



The Dentalium Imperforatum (from Sandwich and 

 its neighbourhood) is also a minute species, and is by no 

 means common. 



The fossil species of the Dentalia are as follow, viz» 

 Dentalium Sexangulum, and Dentalium Fossile, both 

 from Loretto; and the Dentalium Annulatum, Radula, 

 Tnterruptum, and Vitreura, are the sub-terrestrial product 

 of Piedmont. 



