HISTORICAL REVIEW OF THE PELYCOSAURIA. 



The name Pelycosauria was first used by Cope in a description of 

 Clepsy drops fiatalis ; it was given to designate a new suborder of the Rhyn- 

 clioccphalia, based on the supposed absence of the quadrato-jugal arch and 

 the peculiar form of the ischium. He considered the suborder as superior 

 to and including the Tkeriodontia of Owen; he says (44), p. 529: 



"The division Pelycosauria is established primarily on the genera Clepsy drops 

 and Dimetrodon, but their cranial structure renders it highly probable that Edocyn- 

 odon, Payioticlms, and Bolosaurus belong to it. It is also probable that the genera 

 Empedocles, Embolophorus and others determined from vertebrae belong to it, as the 

 latter are frequently accompanied by pelvic bones of the type of that of Dimetrodon. 

 All the genera known from teeth and crania, are of carnivorous habit, excepting 

 Bolosaurus and Diadedes ; they may be referred to a single family on this account, 

 which I call the Clepsydropidce. Bolosaurus will form the type of another family 

 characterized by the transverse position of the crowns of the teeth, under the name 

 Bolosaurida;. Prof Owen has named a group of Triassic and Permian reptiles the 

 Theriodontia, characterized by the mammal-like differentiation of the incisor and 

 canine teeth. The animals thus referred to by Prof Owen probably enter my sub- 

 order of Pelycosauria^ although the structure of their pelvis remains to be ascer- 

 tained. If so, they correspond with my Clepsydropidce, since Prof Owen does not 

 include herbivorous forms in his division. As it is plain that the herbivorous and 

 carnivorous forms belong to the same order, and probably suborder, it becomes neces- 

 sary to subordinate the term Tkeriodontia to that of Pelycosauria. To another 

 division of reptiles from the South African Trias typified by the genus Pareiasaurus 

 Ow., he gives a special name, expressive of the deeply impressed surfaces of the centra 

 occupied by the remains of the chorda dorsalis. As this, or the perforate condition, is 

 characteristic of all the Pelycosauria, it is probable that it is present in Prof Owen's 

 Tkeriodontia also. It is also evident that since the dental characters of Pareiasaurus 

 do not serve to distinguish it as an order from the genera with distinct canine teeth, 

 this group must also be looked upon as a subdivision, perhaps of family value, of the 

 Pelycosauria or other parts of the Rhynchocephalous order." 



It is evident that Cope here regards the Pelycosauria as belonging in 

 the order Rhynchocephalia and his classification stands as follows : 



Suborder : Pelycosauria . 



Family Clepsydropidce : Clepsy drops, Dimetrodon, Ectocynodon, 

 Pariotichus , Embolophorus . 



Tkeriodontia — Clepsydropida. 

 Family Bolosauridce : Bolosaurus, Empedocles, Diadedes. 

 Family PareiasauridcB (?) 



