140 POPULAR CONCHOLOGY. 



7. Glaucus. 10. Scylkea. 



8. Eolis. 11. Tethys. 



9. Tritonia. 12. Doris. 



Family 2. — Dentalidce. ' 



The branchiae of this family are divided into 

 two tufts of soft, flexible, club-shaped filaments, 

 attached to a pedicle on the neck. — Only one 

 genus is known. (See p. 30. note.) 



13. Dentalium. — Shell tubular, regular, 

 smooth or fluted, more or less curved, gradually 



tapering to one end, open at both extremities. 

 Animal long, slender, having a distinct head. — 

 21 recent, 1 fossil species. 



Lamarck thought these animals belonged to 

 the Annulata, but they are now placed amongst 

 the Mollusca. The shell resembles in form an 

 elephant's tusk. Some species are ribbed lon- 

 gitudinally, others transversely, but most of 

 them are smooth. They inhabit the European 

 and Indian seas. 



