OF CONCHOLOGY. 21 



4th, figures 2nd, 4th, 6th and 7th, 

 bbbb. 



Double Teeth, plate 4th, fig. 1st, cc. 



Incurved Teeth are those which are 

 bent round, as in the single tooth of 

 the Solen Siliqua. Plate 4th, ^g. 8th, 



//• 



Middle Teeth. Plate 4th, fig. 4th. 



dd. 



Numerous Teeth, are those small 

 teeth, of which the hinges of all the 

 Area are formed, set in rows. Plate 

 4th, fig. 10th, kk. 



Cavity of the Hinge. The hollow 

 depression in which the ligament of 

 the Ostrea is situated, generally of a 

 triangular form. Plate 4th, fig. 11th, g. 



Ligament of the Hinge, or carti- 

 lage, is that flexible fibrous substance 

 by which the valves are united, and 

 the hinges kept in their proper places; 

 always situated near the beak. Plate 

 2nd, figures 1st, 3d and 4th, III; 

 plate 4th, fig. 3d, n. 



