Vol. 6] Merriam : Mammalian Remains from Mohave Desert. 1 (if) 



animal must have been a common form in the Mohave region in 

 Upper Miocene time, judging by the relatively large number of 

 specimens obtained. 



The camel remains found comprise astragali and proximal 

 phalangeal elements which seem to represent t wo species, one con- 

 siderably larger than the other. The smaller form may represent 

 Procamelus, the larger one Pliauchenia, but a satisfactory deter- 

 mination is not possible with the material at hand. 



The common species of Merycodus, and the horse most abund- 

 antly represented in the collection, taken together indicate that 

 the age of this fauna is approximately Upper Miocene. The 

 camel remains do not negative this determination. It seems 

 improbable that later collections will show sufficient material of a 

 more primitive or less advanced type to indicate that this par- 

 ticular horizon is of Middle Miocene age. On the other hand, 

 the absence of horses distinctly advanced beyond the Merychippus 

 type indicates a period earlier than Pliocene. 



As fragmentary as this collection is, the species included in 

 it imavoidably sugests a close faunal connection with the great 

 plains region during Upper Miocene time. It is also interesting 

 to note that as yet no faunal phase of the Miocene corresponding 

 to the Mohave stage is known in eastern Oregon or in northern 

 Nevada; as also that there is reason to suppose that a cycle of 

 erosion rather than of deposition was in progress in these regions 

 in UpP er Miocene time. 



Transmitted February 24, 1911. 



