236 i:ntroduction to conchology. 



being ventral^ the convex dorsal ; it is also much attenuated 

 posteriori}^, and both ends are open ; the anterior aperture, 

 which is the larger, is simple, and generally oblique, and 

 the posterior, which is also simple, is sometimes slit on the 

 dorsal side. 



The Bentalia were rightly placed by Linnaeus with the 

 mollusca ; not, however, from a knowledge of their anatomy, 

 but in accordance with his plan of referring to that division 

 all animals dwelling in a tubular testaceous shell. In so 

 doing they were mingled with Serpidce, which produce a 

 shell of indefinite growth, and belong to the Annelides, or 

 Earth-worms, and were henceforth removed from them. 

 They are attached to their dwellings by a distinct muscle, 

 and are provided with an elongated sub-cylindrical foot, 

 whereby to make their way in the sand. 



The shells of the Dentalia have not much colour, ex- 

 cepting two large green species, T). dejjhantinum and apri- 

 num, and a beautiful species collected during the voyage 

 of the Samarang, of large size, very richly variegated with 

 rose, olive-green, and white. One or two species are faint 

 yellovr or horny amber, but they are mostly white. 



Many elegant and appropriate devices have been sug- 

 gested by natural objects. The fluted shell of the Den- 



