PRIMITIVE REPTILES 649 



Theromorpha; and the relations of some of the American genera, 

 with and without the second fenestra, are so intimg,te that their 

 family separation is very doubtful. 



My conclusion then is that Paleohatteria and the Proterosauria 

 can not be distinguished from the Theromorpha by ordinal char- 

 acters, and should be united with them. I would provisionally 

 classify the order as follows: 

 Order Theromorpha 



Suborder Pelycosauria 



Family Clepsydropsidae (Sphenacodontidae) 

 Family Poliosauridae 

 Family Edaphosauridae 

 Suborder Proterosauria 



Family Paleohatteridae 

 Suborder Caseasauria 

 Family Caseidae 

 Suborder 



Family Kadaliosauridae (Araeoscelidae) 

 I am aware that this classification is what might be called 

 'horizontal,' rather than 'vertical;' but I also insist that horizon- 

 tal classifications are absolutely imperative until such time as 

 we have more than vague surmises and guesses as to the true 

 lines of phylogeny. Smith Woodard has pertinently criticised 

 the prevalent fashion of making phylogenies to suit every pass- 

 ing hypothesis. And the fashion has found its climax in the 

 'phylogenies' of Steinmann, which I can only understand as 

 proposed in an exquisite spirit of irony. 



PROGANOSAURIA 



The order Proganosauria was proposed by Baur in 1877^ to 

 include Stereosternum and Mesosaurus only, founded chiefly 

 upon the five distalia of the tarsus, a character unknown in mod- 

 ern forms, but one which we have seen is common to all known 

 Permocarboniferous reptiles. Later^ he added Paleohatteria, 



^ On the phylogenetic arrangement of the Sauropsida. Jour. Morph., vol. 1, 

 p. 103, 1887. 



8 Amer. Jour. Sci., vol. 36, p. 311, 1889. • 



