The Shaw Mastodon. 



225 



vertebra of one of the same class of animals, was removed by 

 the writer, who can, therefore, vouch for their genuineness. 



But the greatest value of this find consists, not in the num- 

 ber of animals represented, but in the character of some of 

 the parts. 



The only complete jaw which w T as recovered is not only 

 from a very old specimen (the excessive amount of wear to 

 which the last molars have been subjected proves this), but 

 also, it bears two well-developed tusks. Prof. E. D. Cope has 

 said,* " In some of the species referred above to Mastodon, 

 mandibular tusks are present in the young, and occasionally 

 one is retained to maturity, as sometimes seen in M. americanus. 

 But such individuals are exceptional among their species." 

 Therefore, the most important revelation of this "find" is the 

 presence of two mandibular tusks in an animal which has 

 been satisfactorily proved to be of great age. 



The last right superior molar of this specimen presents an 

 interesting peculiarity. It was evidently broken during life, 

 very early in its use, the heel and its corresponding roots be- 

 ing entirely severed from the main body of the tooth. Being 

 loosely retained in the jaw, it could not be utilized for masti- 

 cation along with the main portion of the tooth. It is evi- 

 dent that, in masticating, the mastodon would bring his teeth 

 together in such ^ manner as to place the lower heel in rear 

 of the inferior molar and, with every movement of the jaw, 

 wedge it away from its proper place. Thus, it was worn on 

 its anterior surface, while the body of the tooth was worn 

 naturally. 



As we have said, hereafter, this find will be noted in scien- 

 tific circles because of this entire lower jaw with its two man- 

 dibular tusks. So far as we know, this is the only jaw of J/. 

 americanus yet discovered, so well provided with incisors. 

 Combining the fact of the unique peculiarities of this early 

 representative of an ancient race with its striking geological 

 position, we have at once an attractive subject for study, 

 speculation, and research.. 



So, the Society has in its collection not only an exceptional 

 find from the extinct local fauna, but a specimen that has not 



* Prof. K. D. Cope, on " The Proboscidia," in the American Naturalist, for April. 

 1889. 



