12 PROCEEDINGS OF THE ACADEMY OF 



January 27. 

 The President, Dr. Ruschenberger, in the chair. 

 Thirty members present. 



Henry A. Muhlenberg, of Reading, Pa., George De B. Keim, 

 Henry Tagg, Chas. S. Whelen, and Charles W. Macfarlane, were 

 elected members. 



Jas. Stevenson, U. S. Geol. Surv., was elected a Correspondent. 



Prof. Cope made some observations on the age of the lignite 

 and other corresponding formations of the West, and especially 

 its supposed equivalent in Northern Colorado. He referred to his 

 determination of the Upper Missouri formation as cretaceous in 

 1868 ; of the Wyoming Bitter Creek series as of the same age in 

 1872. He now added the Colorado strata to the same, on the 

 evidence of vertebrate remains procured by himself during the 

 past season, in connection with the United States Geological 

 Survey under Dr. P. V. Hayden. These remains consisted of 

 DinoHauria of three species, tortoises of five, and a single species 

 of crocodile. Five of the genera were diagnostic. The Dinosauria 

 were referred to the old genus Hadrosaiirus and the new genera 

 Polyonax and Cionodon. The Gionodon arctatus was a large 

 herbivorous saurian, allied to Hadrosaurus, but with a most com- 

 plex and singular type of dentition ; the size that of a horse. The 

 other two species are much larger. 



He also pointed out that the tortoises are identical with species 

 discovered b}' Dr. Hayden in the Fort Union formation of Dakota. 

 He identified the Colorado beds with this group, and believed that 

 they are therefore of cretaceous age, stating that it was the first 

 time such identification had been made. 



Prof. Cope then discussed the age of the coal and lignite forma- 

 tions west of the Missouri River, and stated that Dr. Hayden had 

 divided them into several epochs, viz., the Placer Mountain (New 

 Mexico) ; Canon City (Colorado) ; Fort Union (Dakota) ; and 

 Bear River (W3'oming) ; and that Mr. Meek and himself liad re- 

 garded the Bitter Creek series as distinct from the others. He 

 stated that the stratigraphers and vegetable palaeontologists had 

 regarded all these beds as tertiary, but he believed that the animal 

 and especially the vertebrate pala^ontolog}' required their reference 

 to the cretaceous period. He observed that Mr. Meek had pointed 

 out the cretaceous age of the Bear River beds. LeConte had in- 

 sisted on the same reference for the Caiion City basin. Mr. King 

 and himself had determined that the Bitter Creek coal was creta- 

 ceous, and he had asserted that the Fort Union epoch belonged to 

 the same division of geologic time, in Dakota in 1869, and for 



