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A DICTIONARY OF TERMS. 



Beak. - - The lengthened extremity of the valves in some 



bivalve shells. Certain Tellens have their anterior 



part prolonged into a beak. 

 Bifid. - - Separated down the middle by a slit. The teeth of 



bivalve shells, are often bifid, or double. 

 Bivalve. - A shell with two valves, or pieces, connected by a 



hinge. 

 Byssus. - - A substance spun by the animals of bivalve shells, 



such as the Muscle, and the Pinna ; by which they 



attach themselves to rocks, and other bodies. In 



the Muscle it is called the beard. 



C. 



Canal. - - The continuation of the mouth, or opening, of a 

 shell, into a kind of beak, which becomes tubular, 

 and forms a gutter, or groove. The genus Murex 

 and Strombus, afford examples of a canal. 



Cardinal. - Conchologists apply this word to the central, or 

 principal teeth in the hinges of bivalve shells. 

 The Cockle has four teeth; the two nearest the 

 centre of the hinge, are the cardinal teeth. The 

 Mactra has but one cardinal tooth. 



Cardo. - - See hinge. 



Carina. - - See keel. 



Cartilage. A solid substance harder than flesh, but not so hard 

 as horn. 



Chambered. Having divisions across the cavity in the hollow of 

 the shell, separating or dividing the same into 

 chambers. The Nautilus is a chambered shell. 



Close. - - Shut together, without leaving any opening. It 

 applies chiefly to bivalve shells. The valves of the 

 Solen are open, those of the Muscle are close. 



Columella. The interior part of the lip, situated in the opening, 

 or mouth, very near the axis upon which the spires 

 turn in univalve shells. In some shells, as the 

 Cones, it is smooth ; in others, as the Volutes, it is 

 toothed, or pleated. 



