CORRELATIONS 677 



"From such material as I have examined from this horizon, I am disposed 

 to regard its stage as more strongly marked by the large Pecopterids, includ- 

 ing callipteridoid forms, by the broad Allethopterids and the dilated Neurop- 

 terids. The presence of Allethopteris grandini, Annularia sphenophylloides 

 var. intermedia, which is very closely related to $. filiculme, seems to point 

 toward a level possibly as high as the Pittsburgh coal in the Monongahela 

 formation. But the presence of the forms which, so far as known, appear to 

 include a lower stage makes it seem improbable that the Lawrence plants are 

 of quite so late a date as the Monongahela formation of the Appalachian 

 trough." 9 



In short, they appear to belong to the upper part of the Conemaugh 

 formation. 



One of the critical floras to be compared with the plants of the Ap- 

 palachian section is the flora from Onaga, Kansas, found in the Elmclale 

 formation. Concerning these plants White states: 



"Nearly all the species have been reported from the Permian of Europe. or 

 the Dunkard formation of the United States, though, with the possible excep- 

 tion of Pecopteris newberriana, none are- distinctly characteristic of the Per- 

 mian. It would seem that the Onaga flora should be of later date than the 

 Pittsburgh coal. The evidence presented by this small Onaga flora may, there- 

 fore, be construed, so far as it represents the plants of its horizon, as indicat- 

 ing a stage probably within the Monongahela formation of the Appalachian 

 region, or possibly as high as the lowest part of the Dunkard formation, al- 

 though, with the exception of Pecopteris neivberriana, the collection in hand 

 does not contain any species characteristic of the Permian of the old world 

 and does not signify the Permian age of the Onaga (Elmdale) beds." 10 



That is, plants typical of the Pennsylvanian formations are absent 

 from this local flora, and its whole composition, aside from the one species 

 quoted, is made up of the persistent or transition forms that pass over 

 into the basal Permian. 



The next formation above the Elmdale is the Neva limestone, which 

 carries a Schwagerina fauna and forms the base of the Schwagerina zone 

 of the western part of the Hydrographic basin of the Gulf of Mexico. 

 The top of this zone is found in the Florence flint. Somewhat above the 

 middle of this zone is the Wreford limestone, which is composed of two 

 thick beds of cherty limestone separated by a parting of shale which con- 

 tains fossil fish, land plants, and ostracods. 



In this shale parting White made a collection of fossil plants, regard- 

 ing the age of which he states : 



"An inspection of the rather short list from the Wreford limestone reveals 

 a flora most of whose species are characteristic of the Permian, a small per- 



n Ibid., p. 114. 

 10 Ibid., p. 116. 



