THE RUMINANTS. 



153 



transverse ridges, which fit into the depressions or 

 transverse valleys of the opposite row of teeth, 

 remain throughout life, even though, at a later age, 

 they may become more and more rubbed off and 

 level. The crescents, which become filled with 

 cement and are encased on the outside by enamel, 

 on the inside by dentine (tooth-bone), A, i, a, i, are 



FIG. 21. 



I. Eight upper molar of a calf before it has cut the gums ; i, inner side ; 



A, , the outer lobes of enamel ; /, i, the inner lobes. 



II. The right molar of a calf that has cut the gums, artificially ground ; from 

 behind and the outer side. 



the transverse sections of the flaps of the same 

 name ; B and b are the arched-shaped spaces which 

 likewise become filled with cement, and were ob- 

 viously larger in the thin- walled, uncut tooth. If 

 we weigh the different possibilities of the folds of 

 the outer walls, the form of the crescent, the develop- 

 ment of the side folds and pillar-shaped processes, 



