Case : Vertebrate Fossils from Pittsburgh, Pa. 



239 



raals of considerable size, from 5 to 6 feet in length, if pelycosaurian ; 

 and from 4 to 5 feet, if Diadectid. 



The main interest of these specimens lies in the light which they 

 cast on the geological position of these forms and their geographical 

 distribution. 



Though it has been'pretty generally accepted that the beds in Texas 

 were Permian, there has been no little evidence that they may be 



Fig. 8. Ilium of an undetermined reptile. External view. 



lower. Recently the discussion as to their geological age has been 

 summarized by Beede and Case (Beede 1907, Case 1907). The 

 remains from Vermilion County, Illinois, occur in a region of Pennsyl- 

 vanian rock, but until quite recently it has been supposed that they 

 were buried in the deposits of a Permian River on a Carboniferous 

 land. This idea seems to be wrong {fide Williston). The important 



