437d University of California Publications in Geology [Vol.11 



palaeontologic study it was necessary to make a geological recon- 

 naissance of the formations concerned. The results of this investiga- 

 tion have already been published by Mr. Baker. 2 



In December, 1911, a second expedition under the charge of 

 Mr. Baker visited exposures of Tertiary beds near El Paso Peak on 

 the northwestern border of the Mohave Desert, and made further 

 collections, which added considerably to the list of forms obtained 

 by the preceding expedition. On the December, 1911, expedition, 

 the party with Mr. Baker consisted of J. Guintyllo, S. H. Gester, 

 and G. E. Stone. The geologic section of the region near El Paso 

 Peak has been described by Mr. Baker 3 with the results of his work 

 on the correlation of events in the physical history of the region. 



In January, 1913, H. S. Mourning and J. P. Buwalda visited the 

 exposures of Tertiary mammal-bearing beds in the area north of 

 Barstow, and obtained an excellent collection of the fauna at localities 

 previously visited by Mr. Mourning. This collection was supple- 

 mented by specimens purchased from Mr. Mourning, and by some 

 very useful material which Mr. Mourning kindly presented to the 

 University. 



In December, 1913, and January, 1914, J. P. Buwalda assisted 

 by E. R. Brainard, E. M. Butterworth, and C. Stock, made a further 

 examination of the Tertiary beds in the region of the El Paso Range 

 in the northwestern part of the Mohave region, and obtained a collec- 

 tion of mammalian remains which adds much to our knowledge of 

 the fauna of this section. 



In March, 1915, the Pliocene beds west of the town of Mohave and 

 at the type locality of the Ricardo beds west of the El Paso Range 

 were visited by J. P. Buwalda and the writer. On this excursion a 

 number of important specimens were secured from the lower portion 

 of the Ricardo section at the type locality. 



In the summer of 1915, a party working under direction of J. P. 

 Buwalda worked over exposures of the Ricardo in the El Paso Range 

 and secured a very valuable representation of the mammalian fauna 

 of these beds. In addition to Dr. Buwalda this party included C. L. 

 Moody, Edward Thatcher, and J. M. Douglas. 



2 Baker, C. L., Notes on the Later Cenozoic History of the Mohave Desert 

 Region in Southeastern California, Univ. Calif. Publ., Bull. Dept. Geol., vol. 6, 

 pp. 333-383, pis. 34-43, 1911. 



s Baker, C. L., Physiography and structure of the Western El Paso Eange and 

 the Southern Sierra Nevada, Univ. Calif. Publ., Bull. Dept. Geol., vol. 7, pp. 117- 

 142, pis. 8-10, 1912. 



