Vol. 5] 



Merriam-Sinclair. — Tertiary Faunas. 



195 



As all the John Day species, so far as known at present, 

 appear to be peculiar to the Oregon province, attempts at close 

 correlation have failed. Owing to the lack of common species 

 and the fact that it is often impossible to decide whether certain 

 species are more advanced than others within the limits of the 

 same genus, it is unsafe to base any attempt at very close correla- 

 tion on the presence of common genera alone. 



With the close of the John Day epoch, the total extinction of 

 many genera and even families took place in Oregon. As ex- 

 amples may be cited Mesohippus, Elotherium, Agrioclwerus, 

 Eporeodon, Protapirus, the Carnivora, and many of the Ro- 

 dentia. Not a single species survived. Just how the process 

 of extinction operated in the region under discussion, whether 

 by the dying out of long persistent stocks, or by emigration and 

 by transformation in the ordinary processes of evolution is not 

 fully apparent. This faunal break exceeds in importance all 

 differences existing between the lesser subdivisions of the John 

 Day series. 



THE MASCALL. 



Fauna. — In discussing the Mascall fauna, the possibility of 

 mixture with the overlying Rattlesnake must generally be con- 

 sidered, since bones which have weathered out of the Rattlesnake 

 gravels are frequently found resting on the Mascall, and as most 

 of the material from the latter formation is detached from the 

 matrix it is often very difficult to avoid confusing the two faunas. 



A list of the species previously reported and probably derived 

 from these beds is yiven below. Those marked with an asterisk 

 may possibly be Rattlesnake. 



Lutrictis lycopotamicus Cope. 



Archaeohippus ultimws (Cope). 



Parahippus brevidens (Marsh). 



Protoltippus medkis Cope. 



Protohippus avas Marsh. 



Pliohippus spectans Cope. 



Mcrycliippus isonesus (Cope). 



* Neohipparion occidentale (Leidy). 



* Neohipparion sinclairi (Wortman). 

 Acer other ium oregonense (Marsh). 



* Platygonus rex Marsh. 



* Possibly Rattlesnake. 



