1 68 S. W. WILLIS TON 



in the later Pennsylvanian of this country by known forms from 

 Kansas, and by Marsh's Eosaurus from Nova Scotia, etc. Upon the 

 whole, then, our Permian fauna is sharply and almost completely 

 distinguished from any supposed contemporaneous or indeed any 

 fauna known elsewhere, and may have been evolved wholly in America 

 from known Pennsylvanian forebears. The Texas and Oklahoma 

 Permian deposits were undoubtedly for the most part or entirely 

 those derived from extensive flats of slight elevation, deposits com- 

 posed for the most part of the finest, almost impalpable mud, with 

 little extraneous material, traversed here and there by current channels, 

 and streams which have left for evidence interrupted ribbons of fine 

 or coarse sandstone, and some beds of gravel, with intercalations 

 everywhere of lenticular masses of very fine sandstone of aeolian or 

 quiet water origin. In other words, as has often been said, the depos- 

 its are typical shallow freshwater deposits, gradually merging on the 

 north, as Beede has recently shown, into the shallow marine deposits 

 of the Lower Kansas Permian. Few if any real marine vertebrates 

 are known from all these extensive and varied deposits, since the 

 shark and dipnoan remains not infrequently found may have been, 

 and doubtless were, of fishes already habituated to fresh or brackish 

 water. That there may have been in America contemporaneous 

 forms living on the higher lands of which we have yet no knowledge 

 is doubtless true, but not very probable; the higher grounds of the 

 Wichita Mountains on the north have sent abundant gravel and 

 sand material southward into these deposits, and they surely would 

 also have sent some fragments of distinctive high-land creatures 

 with them had there been any. There is, I believe, in all these 

 deposits, not a single hint of the ancestry of modern reptiles save 

 possibly of the turtles. Nor do I believe that there is any evi- 

 dence of the great phyla of archosaurian and synaptosaurian reptiles 

 here, for I, for one, am pretty thoroughly convinced that the Pely- 

 cosaurs have no genetic relationship- with either of these groups. The 

 origin of the branch leading to the mammals, so far as our knowledge 

 yet goes, was in Africa; there is nothing to prove that it was in 

 North America. What then became of the Permian land fauna of 

 North America ? Not a trace of it is found later in the Mesozoic land 

 fauna of America. Until we know more of the land fauna of South 



