Geology. 399 



5. Tertiary mammalian faunas of the Mohave Desert; by 

 John C. Merriam. Bull. Dept. Geology, Univ. of California, 

 vol. 11, No. 5, pp. 437a-e, 438-585, 253 text figs., 1919.— This 

 paper is of considerable interest to mammalian paleontologists 

 and to students of West Coast Tertiary history. The bulletin 

 contains some of the results of researches made by its author 

 during the past eight years into the animal life of the Tertiary 

 in the southwestern part of the Great Basin. The upper Mio- 

 cene is represented by an assemblage of mammalian fossils con- 

 taining approximately 26 species. The material is derived from 

 the Barstow formation, which is exposed over an area measuring 

 several miles in diameter in the eastern part of the Mohave 

 Desert, southern California, about 75 miles northeast of Los 

 Angeles. The lower Pliocene is known from a fossil fauna of 

 approximately the same number of species collected from the 

 Ricardo formation, the badland exposures of which are situated 

 60 miles to the west of the Barstow locality, at the northwestern 

 edge of the desert along the base of the Sierra Nevada. The 

 Barstow and Ricardo formations are nowhere known to be in 

 contact. 



The fossil materials on which the study is based are stated by 

 Dr. Merriam to be largely fragmentary, connected parts of 

 skeletons being rare. The materials were secured through 

 rather thorough collecting from the two areas of exposures, the 

 size of both of which is relatively small as compared with the 

 extensive areas of fossil-bearing badlands in the Great Plains. 

 Several species of horses are the most significant forms in both 

 faunas and their remains constitute the bulk of the well-pre- 

 served material. Several species of dogs and of camels, and 

 an oreodont are also represented in both faunas. There are 

 described from the Miocene horizon a new species of oreodont 

 and a new variety of horse, and from the Pliocene horizon three 

 new carnivores and a new oreodont. 



The Miocene Barstow fauna has its nearest correlative in the 

 Great Basin in the Cedar Mountain fauna of southwestern 

 Nevada; in the Rocky Mountains and Great Plains regions it 

 seems to have been contemporaneous with the fauna from the 

 Sante Fe beds of New Mexico and probably in part with the 

 Snake Creek of western Nebraska. The Pliocene Ricardo fauna 

 is shown to be approximately equivalent to three mammal-bear- 

 ing, formations of the California Coast Ranges, thereby contrib- 

 uting to a fuller understanding of the relation in time between 

 the deposition of Pacific Coast marine and interior nonmarine 

 formations. The Ricardo has no exact correlative in the Great 

 Basin, being older than the Rattlesnake and Thousand Creek 

 formations. It is near the Blanco of Texas, Snake Creek of 

 Nebraska, Republican River of Kansas and the Alachua of 

 Florida. 



The evidence yielded by the faunas and by the deposits indi- 



