134 Barbour — New Nebraska Mammoth, Elephas hayi.- 



teeth lack the symmetrical development common to mam- 

 moths. They are noticeably constricted back of the anterior 

 prong, and taper posteriorly to If inches (38 mm ). 



Ancestral proboscideans began with 2 simple transverse 

 ridges to each molar tooth. Later forms, such as the masto- 

 dons, had 3, 4, and 5 or more ; intermediate forms, such as 

 stegodonts, bad 6 to 8 or more ; while mammoths had many. 

 ,In E. hayi, there are but 11 transverse ridges at most, the 



Fig. 5. 



d 



f 



Fig. 5. Ascending rami and inferior dental foramina of certain Nebraska 

 Proboscidea. a, Tetrabelodon willistoni; b, Tetrabelodon lulli ; c, Eube- 

 lodon morrilli ; d, Elephas hayi ; e, Elephas imperator ; f, Elephas indicus. 

 From specimens in the collection of Hon. Charles H. Morrill, the Nebraska 

 State Museum. 



last being small, perhaps a heel. This form seems to be an 

 earlier and more primitive type of mammoth than any other 

 known to the State. 



The inferior dental foramen is small, and has a circular 

 border, while in E. imperator it is very large and deeply 

 notched, as shown in the accompanying figures. Although 

 inferior dental foramina differ in individuals, and even 

 between opposite sides of the jaw, the differences shown by 

 the cuts are significant. The ascending rami of our probosci- 

 deans also vary between wide limits. Judging by the large 

 number of varied Nebraska Proboscidea, multiplication of 

 generic and specific names in this group seems inevitable. 



The University of Nebraska, February 15, 1915. 



