634 SCIENCE PROGRESS 



in the Journal of Geology for November and December 191 3 

 (vol. xxi. pp. 728-30), Dr. Broom expresses the opinion that 

 the dicynodonts of the Durna valley, Russia, represent the 

 Cistecephalus zone in South Africa, which likewise contains 

 dicynodont remains of very similar type. If this be so, the 

 Cistecephalus zone will represent the topmost Permian, and the 

 underlying Pariasaurus zone the middle Permian. 



Interesting suggestions with regard to the early evolution 

 of the reptilian skull appear in an article by Prof. Williston in 

 vol. i. No. 8 of Contributions from the Walker Museum. As the 

 result of a study of the skeleton of the lizard-like genus Ara>o- 

 scelis, from the Permian of Texas, the author comes to the 

 conclusion that in the earliest reptiles it is much more probable 

 that the bony skull-roof inherited from stegocephalian am- 

 phibian ancestors should have been perforated only once, 

 rather than twice, on each side, and consequently that the two 

 bony temporal arcades of the modern New Zealand tuatera 

 (Sphenodon punctatus) really represent a more specialised type 

 than does the single arch of lizards. When the matter is put 

 before us in this manner, it is difficult to refrain from wondering 

 why it was never thought of before. Arceoscelis, in which there 

 is certainly but a single arcade, is regarded as the typical repre- 

 sentative of a group — Araeoscelidia — which should include the 

 European Permian genera Protorosanrus and Kadaliosaiirus, and 

 the position of which should be next the Squamata (lizards and 

 snakes). Ichthyosaurs, which never possessed a lower temporal 

 vacuity, and are a primitive group, are not improbably related 

 to the Araeoscelidia. The Permian genus Palceohatteria, on the 

 other hand, which has been associated with the European 

 representatives of the last-named group, is in essential char- 

 acters akin to the Pelycosauria, in which it should typify a 

 special family. If the foregoing view with regard to the con- 

 formation of the primitive reptilian skull be well founded, it 

 follows that the tuatera must surrender its hitherto unchallenged 

 position as one of the most primitive reptiles with which we are 

 acquainted. 



In this connection may be noticed a paper by Mr. Watson in 

 the Ann. Mag. Nat. Hist. ser. 8, vol. xiv. pp. 84-95, on tne 

 bearing of the skull of the extinct Pleurosaurus on the question 

 of the homologies of two of the bones in the temporal region of 

 the skull of lizards. In the tuatera there is but a single element 



