8 REVISION OF THE PELYCOSAURIA. 



"There are some other peculiarities which constitute resemblances of the same 

 kind. The tooth-bearing elements of the roof of the mouth have batrachian character. 

 Such is the densel)- packed body of teeth seen in Dimctrodon ; and so are the teeth on 

 the vomer of Empedodes. There is also a possible existence of epiphyses, judging 

 from various specimens of humeri in my possession of both Pelycosauria and Stego- 

 cephalous forms. 



"In spite of these approximations, the Pelycosauria are distinctively reptilian in 

 their single occipital condyle, ossification of the basicranial cartilage and single vomer. 



"Thus the reptiles and batrachia of the Permian period resembled each other and 

 the Mammalia more closely than do the corresponding existing forms." 



lu the same year as the Second Contribution Cope described (50) a 

 "new division of the Pelycosauria'''' which he called the Cotylosauria and 

 which he evident!}^ regarded as of subordinal rank ; this suborder was 

 fottnded on the supposed presence of double occipital condyles, which was 

 later shown to be fallacious, the appearance being due to the loss of the 

 loosely articulated basisphenoid bone. In the suborder was placed the 

 family Diadectidce^ and to this family was ascribed a new genus, Helodectes, 

 described in the Second Contribution. 



In 1 88 1 (5) Cope gave a catalogue of the Reptilia of the Permian for- 

 mation in the United States in which all forms are placed in the suborder 

 Pelycosauria and no mention is made of the suborder Cotylosauria. The 

 list is as follows: 



Suborder Pelycosauria. ClepsydropidcB — continued. 

 Diplocaulida;: Theropleura uniformis Cope, Texas. 



Diplocaidus salamandroides Cope, 111. triangulata Cope, Texas. 



ClepsydropidcB: oblusidens Cope, Texas. 



Pariotichus brachiops Cope, Texas. Metarmosaurus fossatus Cope, Texas. 



Ectocynodon ordinatus Cope, Texas. Embolophorous fritiUus Cope, Texas. 



ArchcBoboliis vcllicatus Cope, Illinois. Lysorophus tricariiiatus Cope, Illinois. 



Clepsydrops colletti Cope, Illinois. Bolosauridcr: 



vinslovii Cope, Illinois. Dolosaurus stria/us Cope, Texas. 



pcdunailatus Cope, 111. Diadcctida: 



natalis Cope, Texas. Diadectes sideropelicns Cope, Texas. 



Dimetrodon i7icisivus Cope, Texas. phaseoUnus Cope, Texas. 



rectiformis Cope, Texas. Empedodes alatus Cope, Texas. 



biradicatns Cope, Texas. molaris Cope, Texas. 



gigas Cope, Texas. latibuccatus Cope, Texas. 



cruciger Cope, Texas. Helodectes paridens Cope, Texas. 



Theropleura retroversa Cope, Texas. isacii Cope, Texas. 



It will be observed that in this catalogue the batrachian genus Dip- 

 locaidus is included among the reptiles ; it was speedily removed to its 

 proper place. 



In 1882 (54) the genus Edaphosaurus was described, and a new family 

 of the Pelycosauria, Edaphosauridce, was formed for its reception with the 



