518 University of California Publications in Geology [Vol. 10 



known in the Pleistocene deposits of Rancho La Brea. A considerable 

 part of a skull represents a horse, in which the dentition is slightly 

 different from that of the Rancho La Brea Equus occidentalis, and 

 approaches in some respects that of E. pacificus of the Fossil Lake 

 Pleistocene of eastern Oregon. A single separate upper molar tooth 

 of a horse from the same deposit is nearer in type to E. occidentalis. 



A third important collection representing Pleistocene mammal 

 faunas of the Great Basin province is the material secured by 

 Buwalda 4 in the deposits of Manix Lake, a small body of fresh water 

 which formed in the Mohave Desert region, in Pleistocene time. The 

 Manix collection includes six species of mammals and one or more 

 species of birds, together with four types of fresh-water mollusks. 

 Of these forms the mammals include : ( 1 ) a large horse certainly 

 Equus; (2) a somewhat smaller horse; (3) a large camel; (4) a small 

 camel; (5) a fragment representing a proboscidean; (6) an antelope 

 of unknown species. 



The conditions which governed expansion of the lake in which the 

 Manix deposits were formed resemble in a manner those which con- 

 trolled variation of Lake Lahontan, as described by Russell. It is 

 possible that the climatic changes which influenced Lake Manix are 

 identical with those reflected in Lahontan history, and the Manix fauna 

 may be of the same stage as that of Lahontan. 



A fourth Pleistocene fauna from the Great Basin province is that 

 of Fossil Lake in eastern Oregon, obtained in sandy deposits, the strati- 

 graphic relations of which are not satisfactorily described. There has 

 been some mingling of Recent and Pleistocene remains in the lists of 

 material secured from this locality ; but after all necessary subtractions 

 are made, one of the most important Pleistocene mammal and bird 

 faunas of America remains, including a large number of mammals and 

 over fifty species of birds. 



Evidence as to the age of the Fossil Lake fauna is to a certain 

 extent contradictory. According to Gilbert 5 and to Russell, the stage 

 of accumulation of the Fossil Lake deposits is approximately that of 

 Lake Lahontan and Lake Bonneville. Gilbert considered that the 

 highest level of Lake Bonneville corresponded approximately to the 

 last stage of advance of the "Wasatch glacier. Similar evidence seems 

 to be furnished by the relation of the highest level of Pleistocene Lake 



* Buwalda, J. P., Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 443-464, 

 1914. 



s Gilbert, G. K., XL S. Geol. Surv. Monographs, vol. 1, p. 395, 1890; Eussell, 

 I. C, op. tit., vol. 11, 1885. 



