CAPT. D. M. S. AVATSON ON SEYMOURIA. 267 



18. On Set/ inouri a, the most primitive known reptile. By 

 D. M. S. Watson, M.Sc, Capt. U.A.F,, Lecturer in 

 Vertebrate Palseontologj, University College, London. 



[Received September 9, 1918 : Read Novembev 19, 1918.] 

 (Text-figures 1-15.) 



The reptile Seijmouria hayloriensis was originally described 

 from two imperfect skulls, one in connection with a few vertebrae 

 and the shoulder-girdle, by Prof. Broili of Munich, whose excel- 

 lent description made us well acquainted with the structure of 

 the upper and lateral surfaces of the greater part of the skull, and 

 gave general information about the palate, occiput, and anterior 

 axial skeleton. 



In 1910 Williston described as Besmospondylus anomalus a 

 collection of vertebrae, a humerus, femur, and some other bones, 

 which he subsequently recognised as belonging to a young Sey- 

 moitria. In 1911 the same author described a beautifully 

 complete skeleton, publishing a restoration to whose accuracy I 

 am glad to be able to bear testimony. At the same time he 

 suggested that the skull described by Cope as Conodectes favosus 

 was really Seymouria, a determination which is undoubtedly 

 correct. As Cope's description of Conodectes is quite insufficient 

 for recognition of the skull, and Seymoitria is a name universally 

 known, I propose to regard Conodectes as a nomen oiudtim and 

 relegate it to the synonymy. 



In 1914, V. Huene published figures of the type skull of 

 Conodectes, but added nothing to our knowledge; and in 1915 

 I gave a short description of such knowledge of the otic region 

 as covild be obtained from the rather badly preserved skull of 

 Conodectes. 



In danuai-y 1914, through the kindness of Prof. Broili, I was 

 able to make a careful examination and drawings of the type 

 material of Seymoiiria in Munich, which at that time, owing to 

 a new and more complete preparation, showed many features of 

 the structure of the palate and occiput which were not referred 

 to in the original description. 



In 1915 I was so fortunate as to collect some Seymouria 

 material in Texas. The most important of my specimens was 

 found weathered out on the side of a small hillock about 20 yards 

 away from the Cradock bone-bed quarry. I at first supposed it 

 to be a single individual, but have subsequently found that two 

 are represented. The better individual is represented by the 

 pelvis, both hind legs, fifteen presacral, the sacral and the caudal 

 vertebrae in a connected series, and many ribs ; these bones are 

 connected by matrix and are all articulated. Almost certainly 

 belonging to this individual are the atlas and axis and three 



