104 University of California Publications in Geology [Vo L - 7 



The fauna is certainly a rich one and embraces a considerable 

 variety of ungulates of large size which were dependent on a 

 goodly supply of grass and browse. Purely local conditions of 

 dainage may, however, have brought about such a condition. In 

 the fickle streams of the southwest such change of bed may occur 

 in a single season and a deposit laid down under conditions of 

 abundant moisture amounting almost to a peat formation may 

 be left high and dry after a severe freshet to suffer a reversion 

 to almost desert condition. Relatively few of the anserines are 

 found in the collections from the asphalt. Geese of the Recent 

 species become almost upland forms during the rainy season 

 when grass is abundant. Euxenura is, according to Hudson's 

 account in Naturalist in La Plata, a plains-dwelling form of the 

 open pampa at some times of the year. The sand-hill crane, 

 Grus canadensis, is notably a plains feeder in the winter and 

 spring, while the great blue heron, Ardea herodias, has been 

 seen by the author on the dry hillsides in midsummer seemingly 

 in pursuit of grasshoppers. The presence of these birds in the 

 asphalt in the limited numbers found is not then a positive 

 indication of open water or of even marshy ground. The water- 

 worn fragments of wood and the leaves in bedded deposit are 

 such as occur in small steams of the region today when the 

 streams may be more or less intermittant. A rich and varied 

 mammalian fauna is taken by some writers as an indication of 

 mild climatic conditions. Such conclusion seems scarcely war- 

 ranted, however, in view of the present conditions in the desert 

 parts of the world. The writer found deer abundant on the 

 open and thorny desert of Lower California in the region of 

 Cape San Lucas. On the mainland of Mexico, in the desert of 

 Sonora, deer, peccary, and mountain sheep are abundant. The 

 accounts by Roosevelt of game distribution in Africa indicate 

 an abundance and a great variety of game in almost desert 

 regions of that continent. On the Mohave, the Colorado, and 

 the great Nevada deserts, the most ephemeral pools of water, 

 even when highly impregnated with alkaline salts, are the resort 

 of multitudes of waterfowl, while Cope and Shufeldt describe 

 abundant life in the region near Fossil Lake on the Oregon 

 Desert. 



