with Descriptions of New Species. 217 



of the American Museum of Natural History, in allowing 

 liim to measure and study the Cope types of this genus. 

 The illustrations of the new species were made by Mr. 

 Eudolf Weber. 



Geological Sketch. 



In view of the fact that the specimens of fossil verte- 

 brates in the Marsh Collection, from the John Day forma- 

 tion, obtained approximately fifty years ago, are now 

 being intensively studied and described, it is interesting 

 to note that Professor Marsh wrote the earliest general 

 discussion of the geology of this basin of deposition, and 

 that he first proposed the name, John Day, for these 

 deposits. This name has become firmly established in 

 geologic nomenclature in spite of the many substitutes 

 which have been proposed. 



In 1875,^ Marsh wrote: 



'^The Blue Mountains formed the eastern and southern shores 

 of this lake, but its other limits are difficult to ascertain, as this 

 whole country has since been deeply buried by successive outflows 

 of volcanic rocks. It is only where the latter have been washed 

 away that the lake deposits can be examined. The discovery and 

 first explorations in this basin were made by Rev. Thomas Con- 

 don, the present state geologist of Oregon. The typical localities 

 of this Miocene basin are along the John Day River, and this 

 name may very properly be used to designate the lake-basin. 

 The strata in this basin are more or less inclined, and of great 

 thickness. One section, near the John Day River, examined by 

 the writer in 1871, and again in 1873, seems to indicate a thickness 

 of not less than 5,000 feet. The upper beds alone of this series 

 correspond to the deposits in the White River basin. The lower 

 portion also is clearly Miocene, as shown by its vertebrate fauna, 

 which differs in many respects from that above. Beneath these 

 strata are seen, at a few localities, the Eocene beds containing 

 fossil plants, mentioned above. They are more highly inclined 

 than the Miocene beds, and some of them show that they have 

 been subjected to heat. The inferior strata elsewhere are Meso- 

 zoic, and apparently Cretaceous. Above the Miocene strata. Plio- 

 cene beds are seen in a few places, but the basalt covers nearlv 

 all." - ^ 



This basalt is the Columbia lava flow which delimits 

 the upward range of the John Day. The estimate of 

 5,000 feet, made above, seems somewhat excessive, 

 although southerly at Logan Butte the strata exceed 



' 0. C. Marsh, this Journal (2), 9, 52. 



