140 



CHAPTER XXXVI. 



OF THE DENTALIUM. GENUS XXXIII. 



DENTALIUM. 



"Animal a Terebella. Shell univalve, tubular, straight, one-celled, both 



ends pervious." — Linn. 



i HIS genus is very well defined, and easily distinguished from 

 every other. 



These shells are a little tapering, but nearly cylindrical,gene- 

 rally open at both ends, and a little bowed or bending ; several 

 species have a certain number of ribs or ridges running the 

 whole length of the outside : these Linnaeus calls angles. 

 D. striatulum has eight ribs ("/, 129), and is said to be octan- 

 gulattim ; D. elephantinmn with ten is termed deceman gulatwn ; 

 the internal cavity is generally rovmd. 



The animal is nearly similar to some species of Serpula. 



Linnseus has described 8 species, Gmelin has added 1 3, and 

 Dr. Turton 1. Total, 22. 



Lamarck has not divided this genus, but arranges it with 

 his Vermes, after Terebella, Amphitrite, and some of the Ser- 

 pulee ; and describes it as an animal contained in a testaceous 

 solid lube, slightly arched, and open at both ends (see Denta- 

 liwn striohdum, pi. 9. /. 129). 



