DENTITION IN THE RUMINANTS. 55 



tion of which I have examined, into three classes viz. ~Lst. 

 Milk or primitive teeth, developed in a primitive groove, 

 and deciduous. 2d. Transition teeth, developed in a primi- 

 tive groove, but permanent. 3d. Secondary teeth, developed 

 in a secondary groove, and permanent. I hope that other 

 anatomists may verify and extend this line of research, as 

 the results appear to me not only confirmatory of certain 

 great general laws of organisation, but as leading, by the 

 only legitimate path, to the determination of the organic 

 system to which the teeth belong (a subject exciting great 

 interest at present), and as it may enable us in investigating 

 the relations of dental tissue to true bone, to avoid the error 

 of confounding, what there appears to be a tendency to do, 

 analogy with affinity. In recapitulation of the principal 

 facts it may be said : 1. In all the mammalia examined 

 the follicular stage of dentition was observed. 2. The pulps 

 and sacs of all the permanent teeth of the cow and sheep, 

 with the exception of the fourth molar, are formed from 

 the minor surfaces of cavities of reserve. 3. The depend- 

 ing folds of the sacs of composite teeth are formed by the 

 folding in of the edges of the follicle towards the base of 

 the contained pulp, the granular body assisting in the for- 

 mation of these folds. 4 The cow and sheep (and probably 

 all the other ruminants) possess the germs of canines and 

 superior incisives at an early period of their embryonic 

 existence. 



