TEETH OF CARNIVOEA. 785 



which in its texture and mode of growth resembles that of a simple 

 tusk, being continually growing from behind by the addition of new 

 matter produced from the vascular pulp (c) ; so that, were such a tooth 

 not worn away constantly at the point, it would curl up over the face 

 like the tusk of the Babiroussa : and if by accident the opposing tooth 

 in the upper jaw should be broken off, this circumstance in fact really 

 takes place. 



(2265.) But, besides the ivory-forming pulp (c), there is a vascu- 

 lar membrane which exists only upon the anterior surface of the 

 socket, its limits on each side being distinctly marked by a denned line. 

 This membrane secretes enamel, and coats the convex surface of the 

 tooth with a thin layer (6) of that dense substance. From this beau- 

 tiful arrangement it results that, while the anterior end of the tooth is 

 perpetually worn away by attrition against hard substances, the ivory 

 is abraded more rapidly than the enamel that coats it in front ; thus, 

 therefore, the tooth constantly preserves its chisel-like shape, and pre- 

 sents the sharp cutting-edge formed by the layer, of enamel. 



(2266.) The second kind of teeth, composed of bone and enamel, are 

 limited in their growth ; and the entire crown or projecting portion is 

 invested with enamel covering its surface. The teeth of all the CAENI- 

 VOKA, of the QFADRUMANA, and also of MAN, are of this description. 

 From marked differences in their form in different regions of the mouth, 

 such teeth are conveniently divisible into different groups, called re- 

 spectively incisor es, laniares or canine teeth, pseudo -molar es or false 

 grinders, and molares or grinding teeth. 



(2267.) Whatever may be the shape of teeth of this class, their mode 

 of growth is similar to that observed in those of our own species. We 



Fig. 399. 



Growing teeth of a young Lion. 



have chosen, in order to illustrate this, the growing permanent teeth of 

 a young Lion, wherein the different organs employed in their formation 

 are easily distinguishable. The ivory that forms the bulk of the tooth 

 (fig. 399, 6) is formed by the surface of an internal pulp (a) ; and as it 

 slowly accumulates, encroaching upon the central cavity, and penetra- 



SE 



