476 MR. G. A. BOULENGER ON THE [Apr. 19, 



Procoloplion, according to Broom*, has 2.3.4.5.? phalanges in 

 the hind limb. Huxley restored the foot as with one large 

 proximal and four small distal tarsals t- Broom, in Procolophon., 

 has found two proximal elements — tibiale fused with inter- 

 medium, and radiale — and four distals. In Telerpeton there 

 appears to me to have been two bones in the proximal tarsal row, 

 or if thei-e was but one it shows a distinct trace of the fusion of 

 two. The difference between the foot of Telerpeton and that of 

 ProGolophon Avould therefore be restricted to the shape, the former 

 being longer and moi-e slender than the latter. 



In concluding this i-eview of the charactei-s which can be safely 

 ascertained on the material with which I have been entrusted, I 

 must add that I have failed to find any ti'aces of "abdominal 

 ribs," and I feel certain that if any vestiges of a plastron existed 

 these must have been exti'emely slight. Bi'oom, however, has 

 found impressions of a series of plastral bones, apparently in the 

 posterior abdominal region, on one specimen of Procolophon %. 



Affinities of Telerpeton. 



Having reached the conclusion that Telerpeton is closely related 

 to Procoloplion^ it is of course unnecessary to consider its supposed 

 Lacertilian affinities. ISToi- should I have thought it worth while 

 to give reasons foi- its not being a Rhynchocephalian, had not 

 Dr. Broom § recently revived the opinion once held || but since 

 abandoned by Seeley, that Procolojjhon should be referi-ed to that 

 ordei', or at least " somewhere among the jjiimitive Rhyncho- 

 cephalians, — possibly not far from Palceohatteria" a view which 

 has been endorsed by Prof. H. F. Osborn 5[, in whose Classification 

 a new Superorder, Dia2}tosccuria, is established to include the 

 Rhynchocephalia of Zittel, the Pelycosauria of Cope, the Progano- 

 saurict of Baui', and the Procolophonia and Mesosath^na oi Seeley**. 



The thecodont dentition, the absence oi- great reduction of the 

 plastral bones, and especially the pi-esence of ossified prsecoracoids, 

 ai-e chai-acters which are opposed to an association of the Pi-ocolo- 

 phonia with the Rhynchocephalia, whilst in these characters, as 

 well as in the general structui'C of the skull, they agree with 

 Pariosau7'us and Sclerosaurics tt, which, together with Elginia, 

 constitute the gi'oup Pariosauria, united by Cope and by Osborn 

 with the Cotylosaui'ia. 



The Order Ootylosauria was proposed by Cope in 1880 J J as a 

 division of the Theromoi-pha, to include the Diadectida', on the 



* L. c. p. 22, pi. i. tig. 6. t i. c. p. 78, tig. C. 



t L. c. p. 21. § L. c. p. 24. 



II Quart. Journ. Geol. Soc. xxxiv. 1878, p. 803. 



^f " Tiie Reptilian Subclasses Diapsida and Synapsida and the Early History of 

 the Diaptosauria," Mem. Amer. Mus. i. p. 451 (1903). 



** Prof. Osborn's arguments have failed to convince me of the soundness of his 

 view that the Ilesosaiiria have nothing to do with the Nothoscmria. Neustioosatirus, 

 which he places in the latter group, certainljr shows decided affinitj' to Mesosaur^is, 

 and I cannot see any fundamental difference in the rib-articulation of the two types. 



ff Aristodemms Seeley {Lahyrintliodon ruetimeyeri Wiedersh.). 



Xt Amer. Natur. xiv. p. 304. ' 



