THE TEETH OF INSEOTIVORA. 399 



The remaining three premolars are rather small and 

 single ; the true molars are of considerable size, and their 

 points are very long and sharp. 



Ihave purposely avoided giving any dental formula for 

 the Mole : everything turns upon the value which we 

 attach to the term canine ; and I have already given reasons 

 (p. 284) for attaching but little homological importance to 

 its determination. 



Mr. Spence Bate's paper (Trans. Odontol. Society, 1867), 

 valuable as it is in contributing to our whole knowledge of 

 the niilk dentition of the creature, does not appear to me to 

 help us much in the matter of determining the homologies 

 of the canine. 



In a Mole 3J inches long he found eight milk teeth on 

 each side of both upper and lower jaws, as is indicated in 

 Fig. 175. The milk incisors were about one-twentieth of 

 an inch in length, and one two-hundredth in diameter, and 

 were rudimentary in form, consisting of long thin cylindrical 

 tubes surmounted by slightly expanded crowns. All the 

 milk teeth were of this simple form, save only the last in 

 each jaw, which presented crowns with two cusps, and had 

 their roots to some little extent divided into two. 



At the time when these teeth are present the intermaxil- 

 lary suture is very distinct, and there is no doubt that the 

 fourth upper milk tooth, the predecessor of the caniiiiform 

 tooth, is in the intermaxillary bone. 



The teeth had not fairly cut the gum, and the advanced 

 state of the permanent teeth beneath them make it doubtful 

 whether they ever do become erupted. At all events, they 

 can be of no use. 



In many of the order Insectivora the milk dentition is 

 unknown, but we have exemplified amongst them every 

 grade of completeness in its development. Thus in the 

 Hedgehog and Centetes (an allied animal from Madagascar) 



