360 Memoir upon living and fossil Elephants. 



for chewing vegetable substances. This general fart, stifl 

 more clearly brought to light by the labours of M. Tenon^ 

 proved to him of itself, and independently of all those which 

 we are about to develop, that teeth are not organised in the 

 same manner with bones. We all know to what accidents 

 these last are exposed, when they are cut or merely laid 

 bare. 



The summits of the small notches of the laminag will be 

 first worn : — when once worn down to the interior sub- 

 stance, each of these summits will present a circular or oval 

 disk of that substance, surrounded by a circle of enamel and 

 a circle of cortical ; and there will be a range of these small 

 circles by each lamina. 



If the detrition penetrates to the bottom of the hollows 

 which produce the notches, all these small circles will be 

 united into one single stripe of osseous substance, surrounded 

 by a double line of enamel, and the cortical substance will 

 make the whole tour of the tablet of the tooth, and will 

 occupy all the intervals of the stripes. Each stripe will be 

 the section of one of the transversal laminae which compos^ 

 the tooth. 



And if the detrition could go the length of the place where 

 the laminae al! join Into a single corona, the entire tooth will 

 no longer present any thing else than a very large disk of 

 osseous substance, surrounded on every side by a small edge 

 of enamel and another of cortical. 



But the detrition can never go so far, because it never 

 takes effect at the same time upon the whole corona, as the 

 consolidation has not taken place there, and for the foUowr 

 ing reason : 



The tooth, in consequence of its rhomboidal form, and 

 from its very oblique position, presents its anterior part 

 much sooner in mastication than it does its posterior part. 

 The plane or tablet produced by mastication therefore forms, 

 with the common surface of the summits of all the laminae, 

 an angle open b'jhind ; and from thi,> it happens, that, when 

 the front laminae are cut deeply, and form entire stripes, the 

 intermediate laminae do not as yet present any thing else 

 than transverse rows of circles or ovals, and those behind 



are 



