440 University of California Publications in Geology [Vol. 11 



Perognathus fallax pallidus Mearns 

 Perodipus microps C. H. Merriam 

 Perodipus panamintinus C. H. Merriam 

 Dipodomys deserti Stephens 

 Dipodomys merriami simiolus Rhoads 

 Citellus beecheyi flsheri (C. H. Merriam) 

 Citellus mohavensis (C. H. Merriam) 

 Ammospermophilus leueurus leueurus 



(C. H. Merriam) 

 Lepus californieus deserticola Mearns 

 Sylvilagus auduboni arizonae (Allen) 

 Antiloeapra americana (Ord) 

 Ovis nelsoni C. IT. Merriam 



Pallid short-eared pocket mouse 

 Small-faced kangaroo rat 

 Panamint kangaroo rat 

 Big desert kangaroo rat 

 Allied kangaroo rat 

 Fisher ground squirrel 

 Mohave ground squirrel 

 Antelope ground squirrel 



Colorado Desert jackrabbit 

 Arizona cottontail 

 Pronghorn antelope 

 Desert bighorn 



Of the Recent fauna only a few genera are known from the Ter- 

 tiary of the Mohave area. A number of the existing forms, such as 

 the bighorn, are probably immigrants from the Old World, which 

 arrived considerably later than the deposition of the youngest Ter- 

 tiary beds of the Mohave. Unfortunately we have as yet been able 

 to obtain only a very meager representation of the rodent fauna of 

 the Tertiary beds of this region. When this fauna is better known 

 a number of genera now living will undoubtedly be recognized in the 

 Mohave Tertiary. 



OCCURRENCE AND NOMENCLATURE OP THE 

 MAMMAL BEDS 



Geologic sections of the Tertiary beds in the Mohave region are 

 most satisfactorily exposed in an extensive series of deposits in the 

 Barstow syncline north of the town of Barstow, and in excellent 

 exposures around Ricardo Post Office in Red Rock Canon, between 

 the eastern foot of the Sierras and the El Paso Range. These de- 

 posits, with other exposures spread widely over this area, have been 

 referred by C. L. Baker, 4 and earlier in part by 0. H. Hershey, 5 to 

 the Rosamond series on the assumption that they represent one great 

 period of accunmlation. 



While the name Rosamond may be used tentatively for the middle 

 and late Tertiary sediments of the Mohave area it has not been dem- 

 onstrated that the several formations represented are as closely related 

 in their depositional history as they appeared in the first investiga- 

 tions. It seems necessary to discuss the beds in the Barstow syncline 



* Univ. Calif. Publ., Bull. Dept. Geol., vol. 6, pp. 333-383, 1911. 

 s Amer. Geol., vol. 29, pp. 365-370, 1902. 



