2 AMERICAN PERMIAN VERTEBRATES 



of the Texas deposits, opportunity permitting. The Texas Permian 

 fauna is yet but imperfectly known ; of the not less than thirty-five 

 genera of land vertebrates recorded from those beds or known to me, 

 scarcely a third are satisfactorily known; and the region is by no 

 means exhausted. Careful search is sure to yield many new forms 

 and more perfect specimens of others hitherto imperfectly known. 

 I may, however, here express a caution that none save the most 

 experienced collectors need attempt their further exploration with 

 much hope of success. The beds are the most difficult of exploita- 

 tion of any known to me in a field experience of thirty-five years. 

 Usually the fossils are more or less hidden in concretionary nodular 

 masses, almost invisible or indistinguishable to the untrained eye 

 until they have been broken up and weathered, when the inclosed 

 fossils have lost much of their value. Rarely single bones and even 

 whole skeletons are found in clay deposits almost or quite free from 

 matrix, but many such are not to be expected. 



In the following pages I have not thought it worth while to 

 enter extensively into many suggested morphological and taxonomi- 

 cal discussions. In my experience in vertebrate paleontology 

 speculations based upon imperfect and incomplete material, while 

 often fascinating as giving free rein to the imagination, are usually 

 in the end found to be worthless and even misleading. The chief 

 need in the paleontology of the early vertebrates is more facts, 

 many more facts, and I have Httle faith in any system of classifi- 

 cation based upon our present knowledge of these older land verte- 

 brates. I shall hope to know enough about the vertebrates of the 

 American Permian in the course of a few years to venture to present 

 my views of their phylogenies, but at present these views are largely 

 hypothetical. As Dr. Broom, in a letter to me, has said, of a 

 few groups of reptiles, like the dinosaurs, crocodiles, pterosaurs, 

 phytosaurs, rhynchosaurs, etc., we are justified in holding definite 

 opinions; but as regards most of the other groups, often called orders, 

 we are less sure than, we were a dozen years ago. The more recent 

 general classifications of the reptiles by Cope, Osbom, Boulenger, 

 and others have offered suggestions of value, but they are by no 

 means the real solutions of the reptilian and amphibian phylogenies. 

 The recent classifications of Jaekel are not to be taken seriously. 



