430 University of California Publications in Geology [Vol.10 



The Thousand Creek fauna is characterized by the presence of 

 numerous antelopes, some of which are presumably near the modern 

 prong-horn, Antilocapra. Others show superficial resemblance to 

 strepsicerine types of the Old World. The Thousand Creek fauna 

 resembles that of the Rattlesnake in many respects. The horses are 

 similar, and the only representation of the peculiar Thousand Creek 

 antelopes known outside of the typical region are found in the Rattle- 

 snake. The rarity of antelopes in the Rattlesnake may be due to 

 chances of collecting, to difference in habitat, or to somewhat later 

 age of the Thousand Creek beds. 



Antelope remains found recently in the Pinole Tuff-Orinda fauna 

 of San Pablo Bay suggest a relationship between the Thousand Creek- 

 Rflttlesnake and the Pinole Tuff-Orinda stage. 



The Rieardo fauna of the Mohave Desert area is found in a for- 

 mation comprising between 3000 and 5000 feet of sharply deformed 

 strata situated at the eastern foot of the Sierra Nevada Range. The 

 beds in which the fauna occurs consist in a large part of tuffs with 

 desert conglomerates or fanglomerates and other deposits formed on 

 land or in evanescent water bodies. In the thick Rieardo formation a 

 moderate variation of the mammals is noticeable in comparison of 

 different horizons, but the fauna seems to be a unit not divisible into 

 sharply separated stages. 



The species known from the Rieardo are as follows : 



ElCARDO FAUNi. 



Eeptilia 



Testudo, sp. 

 Carnivora 



Canid, small 



Aelurodon, near wheelerianus, n. sp. a 

 Aelurodon, n. sp. b 

 Aelurodon, n. sp. c 

 Aelurodon? or Tepkroeyon, sp. 

 Isehyrosmilus osborni, n. gen. and sp. 

 Felid, large 



Felid, small, not Isehyrosmilus 



Mustela buwaldi, n. sp. 

 Eodentia 



Lepus?, sp. 

 Equidae 



Hipparion mohavense Merriam 



Hipparion mohavense eallodonte Merriam 



Pliohippus tantalus Merriam 



Pliohippus fairbanksi Merriam 



Pliohippus, near mirabilis (Leidy) 



