PRIMITIVE REPTILES 639 



the Theromorpha of Cope as limited by me,i in part the Pely- 

 cosauria of authors, began also in carboniferous times and extend- 

 ed as an order into triassic times in Europe. The third group, 

 the Proterosauria, as represented by Paleohatteria, Proterosaurus 

 and less well known allied forms, began, so far as we know, in 

 the middle Rothliegende of Germany and continued throughout 

 the Permian; it is generally supposed to be the ancestral group, 

 from which all later true reptiles, that is the double-arched forms, 

 arose, and is often included among the Rhynchocephaha, sens, 

 lat. The fourth group, the Proganosauria, as originally defined 

 by Baur and later restricted by Osborn and McGregor, has been 

 accepted by some, though not by all students as an early group 

 of the Sauropterygia, which continued to near the close of meso- 

 zoic times. 



From a study of all these I have endeavored to summarize 

 and correlate those structural characters upon which phylogenies 

 and classification must depend. Many of the known forms are 

 as yet represented by fragmentary and incomplete specimens 

 only, whether those of America or of other lands; of the latter 

 I have little or no autoptic knowledge, a fact less to be regretted 

 since most of them, and those the most important ones, have 

 been described and illustrated by competent students. Of the 

 American forms I have studied with more or less care nearly 

 all the known material, with the exception of that preserved in 

 the museum at Munich, which has been ably discussed by Broih. 

 Of this material I am famihar with complete or nearly complete 

 skeletons pertaining to the following genera: Diadectes Cope, 

 Diasparactus Case, Limnoscehs Will., ^Seymouria Broih, Cap- 

 torhinus Cope, Labidosaurus Cope, Varanosaurus Broili, Casea 

 Will., Ophiacodon Marsh and Dimetrodon Cope. I have also 

 studied the less complete specimens belonging in the following 

 genera: Diadectoides Case, Pantylus Cope, Edaphosaurus 

 (Naosaurus) Cope,^ Sphenacodon Marsh, Clepsydrops Cope, 

 Araeoscehs Wilhston and Animasaurus C. and W., together with 

 the more fragmentary material of nearly all the other known gen- 



1 American Permian Vertebrates, p. 70. 



2 The identity of Naosaurus with Edaphosaurus is now established. 



