656 S. W. WILLISTON 



Seymouria, he would have accepted both Hylonomus and Petro- 

 bates as reptiles. However, Baur's more decided views as the 

 reptilian nature of the Microsauria were accepted by not a few 

 authors, and their reptilian affinities, or at least those of some 

 of the forms called Microsauria, have been recognized by all. 

 Indeed, by some writers the Microsauria are considered the an- 

 cestral type from which some if not all reptiles arose. Never- 

 theless, they have been generally retained among the Stego- 

 cephalia, either under the ordinal or subordinal term Lepospon- 

 dyli, proposed by Zittel, or the earlier Microsauria of Dawson. 

 That the group Microsauria, as usually defined, is a heterogeneous 

 one is now admitted, but sufficient evidence to serve as a secure 

 foundation for its disintegration and the redistribution of its 

 various forms on a scientific basis has not been forthcoming; 

 and I doubt whether any proposed scheme will stand the test 

 of time, or be worth serious consideration. The very recent 

 scheme of classification proposed by Jaekel, in which he gives 

 to the group a class value, dividing it into various orders, betrays 

 such a regrettable lack of knowledge that it may be disregarded. 

 A few years ago M. Thevenin described a peculiar reptile-like 

 form from the Stephanian or uppermost carboniferous of France 

 as Sauravus costei, referring it to the Rhynchocephalia.^^ In 

 the following year I redescribed^^ an allied form which previously 

 had been described and figured by Cope^^ under the name Iso- 

 dectes punctulatus, from the Linton beds of Ohio, of middle 

 Pennsylvanian age, referring it, together with Sauravus costei 

 provisionally to the Cotylosauria. As a comparison of the 

 specimen upon which Cope's remarks were based with the real 

 type of the species showed specific differences at least, I gave 

 to his plesiotype the name Isodectes copei, later changed to 

 Eosauravus copei^^ when it became evident that the species 

 could not be referred to the Texas genus Isodectes, of much 



22 Annales de paleontologie, 3, p. 19, 1907. 



2» Journal of Geology, 16, p. 395, 1908; Moodie, Proc. U. S. Nat. Mus., 37, p. 

 11, 1909. 



2* American Naturalist, 1896; Proc. Amer, Phil. Soc, p. 88, 1877. 



25 Bull. Geological Soc. Amer., vol. 21, p. 272, 1910; Case, A revision of the 

 Cotylosauria of North America, p. 31, 1910. 



