PERMIAN. 413 



PALEONTOLOGY. 



The value of the paleontological evidences of the age of a formation, when 

 rightly interpreted, is acknowledged by every one to be of the highest import- 

 ance. The life history of the globe is one, and the development from the 

 lowest to the highest orders went on from age to age. The forms that were 

 characteristic of one system gradually became extinct, and other forms came 

 in and took their places. The older forms gradually became extinct and the 

 newer as gradually came in. Some of the forms were much longer lived than 

 others, and would pass through an entire system, and sometimes even longer, 

 while others would be restricted to a single series. The old Paleozoic forms 

 that had come of from the deep past were gradually giving place in the Per- 

 mian to the Mesozoic forms that were to be so abundant as the time went by. 

 The Permian was a period of transition. So greatly blended are the two 

 forms — the old and the new — that it is still an open question as to whether it 

 should be placed with the Paleozoic or with the Mesozoic groups. At places 

 the older forms predominate, and when that is the case it is contended that it 

 ought to be placed with the Paleozoic group. At other places the newer 

 forms are more numerously represented, and then it is contended that the 

 series should be placed with the Mesozoic. 



Dr. White, who described the invertebrate fossils taken from the Wichita 

 Beds and lower part of the Clear Fork Beds, found the older forms largely 

 predominating, and did not hesitate to refer the Permian to the Paleozoic 

 group. He says, however, that if two of the fossils found therein had been 

 submitted to any paleontologist he would not have been warranted in refer- 

 ring them to an earlier period than the Trias, if he had followed the usually 

 accepted standard of reference; and that without these two fossils the others 

 might with equal propriety have been referred to the Coal Measures. The 

 very fact that the two types occur in the same strata is the reason I insist on 

 calling the beds Permian; and whether it shall be referred to the Paleozoic 

 or the Mesozoic is a matter that will not be discussed in these pages. Some 

 writers have evaded the issue by calling certain strata Permo-Carboniferous. 

 If one would make special selections from the fossils of the Permian in Texas 

 he could with equal propriety refer the strata from which they were taken 

 to either the Coal Measures, Permian, or Triassic; but when they are taken 

 together there can be no other conclusion reached than that the strata be- 

 long to the Permian. They can not be referred to the Carboniferous, because 

 they contain not only the Carboniferous fauna, but also the forms found in 

 the Triassic. They can not be referred to the Triassic, because they contain 

 forms that belong to the Coal Measures, as well as forms that are characteristic 

 of the Permian. Therefore the only reasonable reference is to the Permian 

 as the transition period between the two others. 



