300 CAPT. D. M. S. WATSOX ON SEYMOURIA, 



In the Cotylosaurs this division corresponds with that which 

 I have previously founded on the character of the otic notch, 

 and the mode in which a vertically placed quadrate is arrived at. 

 I have recently found that this division on the character of the 

 otic notch applies to all reptiles, affording a sharp distinction 

 between the Anomodonts and all othei- groups, so that we have 

 now two quite independent series of characters, the otic notch 

 and the structure of the fenestra ovalis, which allow us to split all 

 reptiles, Seymouria excepted, into two- groups. Seymouria itself 

 shows chai-acters definitely connecting it with one of these. 



The curious way in which the structui-e of Seymouria is built 

 up of perfectly well-developed amphibian characters and equally 

 decisive reptilian features, those of intermediate type being very 

 rare, afibrds a magnificent example of the way in which the 

 evolution of great groups may liave taken place by the rapid 

 change of all the definite morphological entities of which it 

 may be regarded as made up, the chai:iges occurring quite inde- 

 pendently and over a considerable time, the passage from the 

 structure of the more primitive to the advanced group being quite 

 gradual when viewed as a whole, but when further considered 

 and analysed found to depend on a rapid evolution of separate 

 regions apparently independently of each other. 



I hope that this study of '''feymouria will be regarded as placing 

 beyond dispute the origin of the reptiles from the Embolomerous 

 Labyrinthodonts. 



I wish to express my thanks to the Percy Sladen Trustees, who 

 paid the expenses of my visit to Texas, to Prof. S. ^^^ Williston, 

 who allowed me to study freely the superb collection of Lower 

 Permian Tetrapods which he hasbniltup in Chicago, to President 

 Osborn and the Staff of the American Museum for similar 

 privileges there, and to Prof. F. Broili, who placed the treasures 

 at Munich at my disposal. I regret that circumstances at 

 present forbid my obtaining his permission to jDublish a descrip- 

 tion of the Seymouria material of which he ga.ve so excellent a 

 description. Finally, I wish to thank my wife for editing this 

 paper and thereby removing many obscurities. 



Literature. 



Beoili, F. 1904. " Permische Stegocephalen und Reptilien aus 

 Texas." Palseontographica, Bd. li. pp. 1-120. 



. 1908. " Ein montiertes Skelet A'on Lahidosaurus hamatus 



Cope, einen Cotylosaurier aus dem Perm von Texas." 

 Zeitsch. deutsch. geol. Gesell. Bd. Ix. Heft 1, pp. 63-67. 



Broom, R. 1913. " Studies on the Permian Temnospondylous 

 Stegocephalians of North Ameinca." Bull. Amer. Mus. 

 Nat. Hist. vol. xxxii. pp. 563-595. 



Case, E. C. 1911. A Revision of the Cotylosauria of North 

 America. 



