HISTORICAL REVIEW / 



The order Pareiasauria was divided into the families Pareiasauridte, Pario- 

 tichtdee., and Diadecttdee. 



In November of 1903 appeared Osborn's detailed paper on "The Reptilian 

 Subclasses Diapsida and Synapsida and the EarlyHistoryof theZ)/a/'<ojaMna" (55). 

 The position of the Cotylosauria is the same as given in the preliminary papers by 

 Osborn and McGregor. 



Broili's description of the Permian collections in Munich appeared in the 

 " Paleontographica" in 1904 (4). His arrangement of primitive reptiles is as follows: 



Order Rhyncocephalia. 



Lysorophtts tricarinatus. 

 Order Theromora. 



Suborder Cotylosauria. 



Family Pareiasauridcs. 



Genus Labidosaurus, Seymourta. 

 Family Otocalidee. 



Genus Oiocaelus, Conodectes. 

 Family Diadectidee. 



Genus Diadectes, Empedias, Chtlonyx, Bolbodon. 

 Family Pariotichidce. 



Genus Isodecies, Captorhinus, PartoUchus, Pantylus, 

 Hypopnous, Helodedes. 

 Order Pelycosauria (Theriodontia). 



In 1904 Boulenger published a description of Telerpeton elginense (4), in which 

 he suggested a diphyletic origin of the reptiles from the amphibia. In this paper 

 Boulenger says: 



"What we know of the American Cotylosauria shows them to be a type closely 

 related to the Pariosaurians, though differing from them in at least one important 

 character, the absence of the cleithrum. The same may be said of the Procolo- 

 phonia (Procolophon and Telerpeton), and therefore, these must be regarded, in the 

 light of our present knowledge, as pertaining to the group for which the earlier 

 Cotylosauria should be used. 



"The order Cotylosauria may be defined as thecodont reptiles with the temporal 

 region roofed over (without or with a single temporal foramen), with clavicles and 

 interclavicle, with coracoids and precoracoids (epicoracoids), without or with a 

 very vestigial plastron, and with the number of phalanges as in the typical reptiles. 

 The absence of the cleithra and the presence of more than 2, 3, 3, 4, 3, phalanges 

 distinguishes them from the Pariosauria; the second character and the roofing 

 over of the postorbital part of the skull distinguishes them from the Anomodontia; 

 whilst the presence of the ossified precoracoids and the absence or the extreme re- 

 duction of the plastron separates them from all the other primitive orders, such 

 as the Rhyncocephalia, Plesiosaurta, Thecodontta, etc., with the possible exception 

 of the Pelycosauria which also flourished in the Permo-Triassic time. 



"The order Cotylosauria would comprise four families, the definition of the 

 American types being derived from the contributions of Cope and Case. 



"A. Supratemporal roof broad, orbit small, nearly in the middle of the length of the head; 



no latero-temporal vacuities; upper surface of the skull more or less sculptured. 

 Teeth small not transversely expanded, in two rows in the posterior part of the 



jaws I . Partotichidtt 



Lateral teeth large, with the crowns expanded transversely to the axis of the jaws in a 



single series 2. Diadectida 



