1891.] 



BRITISH REMAINS OF HOMCEOSAURUS. 



169 



classification of the Rhynchocephalia, Lydekker ^ and Zittel ^ the 

 former has overrated the importance of these characters in assigning 

 to Homoeosaurus and alHes the rank of a suborder, opposed to Sphe- 

 nodon, Rhynchosaurus, and Hyperodapedon ; while the latter has 

 underrated their importance in uniting Homoeosaurus and Sphenodon 

 in one and the same family. Homoeosaurus deserves to stand as the 

 type of a distinct family, in the immediate neighbourhood of the 

 Hatteriidce, to which it is more nearly related than to the Rhi/ncho- 

 sauridce or than are the latter to the Hatteriidce. 



The classifications of the two authors above referred to differ as 

 follows : — 



1. Lydekker. 



r Fam. HomcEOsauridcB. 



iSubord. Homoeosauria \ „ Vlciirosauridm. 

 . . , „ , .,•{',; '^ilhmMidcB. 

 Subord. Sphenodontina " t,. i J 



^ y „ nnyncfiosauridcs. 



Ord. Proterosanria ,, Protcrosauridm. 



Champsosaurus is not mentioned, but forms a third Suborder 

 (Simccdosauria) of the Rhynchocephalia iu the author's more recent 

 Manual ^ 



2. Zittel. 



Ord. 



Rhynchocephalia 



, Subord. Rhynchocephalia 8. s. j ^^'°- Spfienodontid^ 



Subord. Proganosauria 



Proterosauridm. 

 MesosauridcB. 

 Champsosa urida. 



Both these arrangements appear to me unsatisfactory. The Prote- 

 rosanria are allowed ordinal rank by Lydekker merely provisionally 

 and " in deference to the views of Prof. Seeley." But his definition 

 of the Order is not diagnostic, for such characters as " Cervical ver- 

 tebrae much elongated" and " Posterior caudal vertebrae with divided 

 neural spines " can certainly not be meant to characterize an Order. 

 As to the latter character in particular, I have to remark that it 

 occurs in certain Lacertilia, and is particularly marked in a genus 

 which, one would think, might not have escaped notice. I now ex- 

 hibit a skeleton of Lacerta ocellata, with the object of showing the 

 curious division of the neural spine of some of the caudal vertebrae 

 (fig. 2, p. 170) into an anterior and a posterior part, as believed to 

 he characteristic of the Proterosauria. In the specimen exhibited, 

 the caudal vertebrae, from the 9th to the 19th inclusively (the rest of 

 the tail being regenerated), bear two neural spines, the anterior 

 directed obliquely forwards, the posterior directed obliquely back- 

 wards. Both are processes of the posterior moiety of the vertebra 

 (the caudal vertebrae of these and other fragile-tailed Lizards being 

 divided into two), thus showing that the division of the spine has 



' Cat. Foss. Rept. i. p. 290 (1888). 



■' Handb. Pal. iii. p. 583 (1889). 



' Nicholson and Lydekker, Man. Pal. ii. (1889). 



