REPTILIA : THEROMORPHA 71 



Theromorpha to include the two suborders Pelycosauria and 

 Anomodontia, the latter term used in a wider sense than is now 

 recognized. As a usual thing, priority is not much respected 

 in the use of classificatory terms above the genus. As proposed 

 by Cope the suborder Pelycosauria was coextensive with the 

 family Clepsydropidae, to which after was added the Poliosauridae 

 by Case. If we extend the term to include all the therocrotaphic 

 reptiles from the Permian of America, from Naosaurus to Araeo- 

 scelis, as an order it displaces the ordinal term Theromorpha, 

 unless the order be retained to include the African forms grouped 

 by Broom in his order or superorder Therapsida; in the latter case 

 it would take precedence over all others. If, later, it is shown 

 that all the American forms are coherently distinguishable by 

 valid group characters from the Therapsida, and provided that 

 no higher rank is given to the whole assemblage than an order, 

 the American forms, by the extension of the boundaries of the 

 suborder Pelycosauria, may be distinguished from the African 

 suborder Therapsida. But there is little probability of any 

 unanimity of opinion in this. Broom insists that the groups 

 Therocephalia, Dromasauria, etc., are at least of subordinal value, 

 and certainly the differences between the phytophagous Casea 

 and Dimetrodon are as great as between the Dromasauria and the 

 Therocephalia, each of which would likewise be entitled to subordinal 

 distinction. 



It is, however, quite impossible to satisfactorily distinguish 

 all the imperfectly known forms at present, and as it is quite 

 certain there are many more therocrotaphic forms to be discovered 

 in Africa and North America, to say nothing of the forms that may 

 be expected from other parts of the world, it seems most expedient 

 to resuscitate the term Theromorpha for our American genera at 

 least; and as nothing much is to be gained in the present state of 

 our ignorance by dividing our American genera into various 

 suborders, the term Pelycosauria may be held in abeyance, or used 

 only to distinguish the long-spined theromorphs. 



I recognize, then, the following groups of American theromorphs: 

 Sphenacodontidae (Clepsydropidae), Poliosauridae, Edaphosauri- 

 dae, Caseidae, and Araeoscelidae. 



