1919] Merriam: Tertiary Mammalian Faunas of Mohave Desert 463 



by Dr. Hayden from the Niobrara sands. The horizon is presumably 

 Upper Miocene. The lower jaw and M 2 figured by Leidy 23 show form 

 and dimensions closely similar to those of a specimen obtained by 

 Peterson 24 from beds at Whistle Creek, Nebraska, possibly belonging 

 to late Miocene or Pliocene deposits. 



A portion of a lower jaw, no. 19402, with P 3 to M 2 inclusive, from 

 the Barstow beds of the Mohave region, California, very closely re- 

 sembles the type of Leidy 's Canis temerarius from the Nebraska 

 formation and also resembles the specimen from Whistle Creek, 

 Nebraska, referred to this species by Peterson. 25 M. 1 of the Mohave 

 specimen very nearly approaches in form and dimensions the original 

 figured specimen of Canis temerarius Leidy, and the Mohave species 

 is almost identical in form and dimensions with the corresponding 

 parts of the specimen described by Peterson. 



Fig. 7. Tephrocyon, near temerarius (Leidy). A portion of the mandible 

 with dentition shown in superior and lateral views. No. 19402, natural size. 

 Barstow Miocene, Mohave Desert, California. 



The specimen from the Barstow beds (fig. 7) represents a species of 

 Tephrocyon differing slightly from those thus far known in the Great 

 Basin region. The relationship of this form to the genus Tephrocyon 

 is shown in the large size of the metaconid and of the crushing heel 

 of M la and in the presence of a well developed paraconid with a large 

 antero-external shelf on the cingulum of M 2 . 



The Barstow form is very close to the typical T. temerarius but 

 may be separated by subspecific or specific characters when better 

 known. In the Mohave form M x seems a little heavier than in Leidy 's 

 type. 



23 Leidy, J., Jour. Acad. Nat. Sci. Phila., ser. 2, vol. 7, pi. 1, fig. 12, 1869. 

 2* Peterson, O. A., Mem. Carneg. Mus., vol. 4, p. 268, 1910. 

 25 See comparison in Notes on the Canid Genus Tephrocyon, J. C. Merriam, 

 Univ. Calif. Publ., Bull. Dept. Geol., vol. 7, pp. 366-367, 1913. 



