ON THE VALUE OF THE EVIDENCE FURNISHED BY 

 VERTEBRATE FOSSILS OF AGE OF CERTAIN SO- 

 CALLED PERMIAN BEDS IN AMERICA 



E. C. CASE 



In 1876-77 Cope referred certain beds in Illinois and Texas, bear- 

 ing vertebrate fossils, to the Permian Age. This has stood almost 

 without challenge until very recently and has had a very considerable 

 effect on the literature of the Permian. The recent discovery by 

 Mr. Raymond of reptilian remains, of the same character as those 

 referred to the Permian from Illinois and Texas, in the Coal Meas- 

 ures of Pennsylvania^ renders it desirable to re-examine the evidence 

 upon which the position of the beds was determined. The conflict- 

 ing evidence of invertebrates and plants will not be discussed as 

 they will be considered in the accompanying papers. 



In re-examining the evidence for the age of these beds it seems 

 necessary to consider two points: 



I. The morphological comparison of the North American forms 

 with those of known Permian Age from Europe and other continents. 



2. The possibility of the introduction of reptilian life at an age 

 earlier than the Permian. 



In discussing the first question it will be best to pass in review 

 the evidence upon which Cope based his determination of the Per- 

 mian Age of the beds. The scope of the article will not permit dis- 

 cussion of the details of comparative anatomy and so the arguments 

 will be based on conclusions which have been reached by various 

 anatomists, leaving the details to another time and place should a 

 discussion arise. 



Cope's evidence: The first mention of vertebrate remains from 



Illinois was in 1875:^ 



A remarkable peculiarity of the vertebrae of the series is the longitudinal 

 perforation axial of the centrum. They present the character observed in Arche- 



1 Science, Vol. XXVI, December 13, 1907. 



2 Proc. Acad. Nat. Sci. Phil., 1875, p. 440. 



572 



