1914] Merriam: Tertiary Mammals f rom Northeastern Nevada 279 



Truckee beds, discovered a considerable part of a mastodon cheek- 

 tooth 3 in the section near "Verdi, Nevada. Proboscideans are absolutely 

 unknown in the John Day Oligocene, but range from the Mascall 

 Middle Miocene up to Pleistocene in the Great Basin. It is clear that 

 the correlation of the John Day and Truckee is not justified. No 

 Oligocene is certainly known in the Nevada region. Mr. Buwalda 

 believes that the Truckee beds are possibly of the same age as the 

 Cedar Mountain Miocene not far to the south, but fully satisfactory 

 evidence of identity in stage is not at hand. 



Whether or no the Truckee and Cedar Mountain beds are of the 

 same stage, it is true that deposits of Miocene age seem to range east- 

 ward from near the western border of the Great Basin, as stated by 

 King in the Fortieth Parallel Survey report. The deposits of the 

 McKnight locality are evidently not widely different in age from those 

 of Cedar Mountain and Truckee, and extend the range of the Miocene 

 considerably to the east. 



DESCRIPTION OF MATERIAL 

 Merychippus, sp. 



The most common remains in the collection from the McKnight 

 locality represent a horse of the genus Merychippus. A number of 

 foot-bones and teeth available seem all to be derived from individuals 

 of the same species. The recognizable specimens comprise the first 

 and second phalanges, a navicular, and a well preserved lower molar. 

 The phalanges (fig. 2) may be matched in size and form by specimens 

 from the Mascall and Virgin Valley Middle Miocene of eastern Oregon 

 and northern Nevada. They may also be matched almost exactly by 

 specimens from the Upper Miocene Mohave beds of the Mohave Desert 

 area, but seem a little smaller than the average of these specimens. 

 The phalanges are a little more constricted than some available from 

 the Cedar Mountain fauna. 



A lower molar, M 1 1 (fig. 1), also compares closely in size and form 

 with specimens from the Mascall and from the Mohave. It appears 

 rather small for average specimens of the Mohave fauna. As the 

 characters of single lower molars of the species of Merychippus are 

 not always clearly diagnostic, it is difficult to make a definite specific 

 determination of this specimen. 



s Buwalda, J. P., Univ. Calif. Publ. Bull. Dept. Geol. (In press.) 



