70 WISCONSIN AGEICULTUEE. 



crowding it forward, while it stands entirely separate from tlie 

 one behind. 



The posterior tooth is evidently in a growing condition. It 

 has four transverse ridges, each divided in the usual manner 

 into two cusps ; the last ridge is nearly hidden beneath the bone, 

 not having yet fully crowded itself out. The two anterior cusps 

 are by far the largest and most elevated : the tooth is much the 

 largest and broadest in front. This tooth is but very little worn, 

 and only on the two anterior prominences. 



The portion of the left branch of the jaw remaining, extends 

 back to the origin of the first tooth, exhibiting the broad smooth 

 channel or groove occupied by the tongue. The abrupt deflec- 

 tion of this groove anteriorly, and the want of a beak or prolon- 

 gation of the bone in front, excludes this fragment from the 

 Mastodon longirostris ; and the proportionate breadth of the 

 teeth as clearly indicate that it does not belong to the Mastodon 

 angustidens. Mr. Lapham therefore concludes that the specimen 

 belongs to the Mastodon giganteus. 



On referring to works on the Mastodon giganteus, we find it 

 stated that there are six molar teeth in each branch of the jaws. 

 These teeth are produced at different times, those in front being 

 shed while others are forming behind. Of these teeth the fifth 

 (as described by Dr. Warren in his work) corresponds with the 

 first in the specimen of Mr. Lapham. This indicates an animal 

 of considerable age, having already shed four teeth on each side 

 of each jaw, or sixteen teeth in all. The middle tooth in the 

 specimen corresponds with that of the sixth and last of Dr. War- 

 ren. So that the posterior tooth is one not before observed in 

 any of the bones heretofore found. 



If we admit that the teeth advance as the animal increases in 

 age, those in front being shed while others are formed in the 

 posterior portion of the jaw, we see no good reason why this 

 process may not be continued indefinitely, and the ultimate 

 number of teeth be regulated by the age and healthful condition 

 of the individual. In this view of the subject, there are no per- 

 manent molar teeth. Disease or death may arrest the process 

 of dentition at any stage of its progression ; and there may be 



