Per mo-Carboniferous Ammonoids of the Glass Mountains 2^ 



species of Medlicottia was found, which White^ identified with his 

 Medlicottia Copei. The locality near the falls on Salt Croton Creek 

 has furnished Perrinites HUH Smith and a number of undescribed 

 species of Popanoceras (probably Stacheaceras) and Medlicottia 

 which are supposed to be identical with similar forms found at the 

 third locality, the Military Crossing of the Big Wichita. The am- 

 monoids discovered at this last place are: Medlicottia Copei White, 

 Paralegoceras baylorense White sp., Stacheoceras Walcotti White sp., 

 and Perrinites Cumminsi White sp. White recognized the fact that 

 his ammonoids showed some very near relation to those of the Sosio 

 beds of Sicily and of the Productus limestone of India, but notwith- 

 standing this he expressed the somewhat surprising belief that those 

 beds of Sicily and India might perhaps belong to the Upper Coal 

 Measures, strata that he found below his Texan Permian. As we 

 shall see later on, he reversed the real conditions. White did not 

 know the works of Murchison, Verneuil and Keyserling, Karpinsky^ 

 and Krotow, or he would have perceived that those forms which he 

 thought to be Mesozoic types are in reality typical Permian genera and 

 that there was no commingling of Mesozoic and Carboniferous types 

 at all. 



When we study the fauna described by White we see that the most 

 important fact is the occurrence of highly developed Cyclolobinae in 

 the form of Perrinites, while other decidedly Permian forms are Med- 

 licottia and that group of Stacheoceras which is represented by St. 

 Walcotti. The occurrence of Perrinites is of special significance as it is 

 by far the most common of all the species found at the Military Cross- 

 ing, the same as is the case with Perrinites in our Leonard formation. 



Perrinites has been found also at the falls of the Salt Croton Creek, 

 Kent County; but this species, P. Hilli Smith, is very different from 

 P. Cumminsi and exceedingly similar to P. vidriensis; so much so that 

 for some time I doubted if it were not the same species. This resem- 

 blance justifies us in supposing that the beds of P. Hilli and our Leon- 

 ard formation are of the same age. The former ones belong to the 

 middle part of the Double Mountain formation while the beds at the 



'White, The Texan Permian, p. 21. 



^He received this work .after his paper had gone to the printer. 



