KSTIMAIING THK A(;E OK THE .MASTODOX 3 



other. They are faintly indicated also in the waving surface of the 

 dentine of the tusk (Fig. 3). 



On the hypothesis that these are actual annular increments of 

 growth, the right tusk (Fig. 3, .1) consisted of about twenty-eight 

 segments, which allowing for the milk dentition and for the part 

 worn off at the tip would assign to the Warren ^lastodon an age 

 of perhaps thirty years. 



Similar annular constrictions are ol)served in the tusks of the mam- 

 moth from Alaska ; and are also indicated in the tusks of the African 

 elephant. Since the age of the Indian elephant and the rate of tusk 

 growth is definitely known, the identification of similar concentric 

 annular growths would be the means of testing the value of this 

 hypothesis. 



Fig. 1. Skeleton of Warren Mastodon as recently mounted in the American 

 Museum of Natural History. 



Fig. 2. Anterior view of skull of Warren Mastodon showing the true position 

 of the tusks in the mastodon. 



Fig. Inferior and external views of the right and left tusks, showing the sup- 

 posed annual growth segments. 



A, right tusk viewed from the outside and somewhat from below. 



B, left tusk, direct external or outside view. 



