4 68 SCIENCE PROGRESS 



to the new genus Rhinosuchits, of which, however, the type 

 is a German species. 



One of the foregoing determinations is unlikely to remain 

 unchallenged, for in a paper published in the Zoological 

 Society's Proceedings (1908, p. 605) Professor H. G. Seeley 

 considers that Pariasaurus itself carried a dermal armour, 

 taking the form of one median and two shorter lateral rows 

 of ovate bony scutes along the back. 



In a second paper published in the same journal (p. 611) 

 Professor Seeley gives additional particulars concerning the 

 skull and dentition of the South African anomodont genus 

 Diademodon, in which the cheek-teeth are regarded as presenting 

 remarkably mammal-like features. 



At the close of a communication on the origin of the mammal- 

 like reptiles contributed to the Zoological Society's Proceedings 

 for 1907 (p. 1047), Dr. Brown remarks that 



The mammal-like reptiles form a well-defined group whose 

 earlier members show so much affinity with the primitive 

 diaptosaurians and with the higher cotylosaurians as to render 

 it highly probable that from some cotylosaurian ancestor all the 

 later reptiles are descended. On the other hand, the higher 

 mammal-like reptiles approach so closely to the mammals that it 

 is not always possible to distinguish between them. Tritylodon 

 is held by many to be a reptile ; by others it is believed to be a 

 mammal. Dromathcrium, Microconodon, and Karoomys are gene- 

 rally believed to be mammals, but it is just possible they may be 

 reptiles ; while Sesamodon and Melinodon, which are believed to 

 be cynodont reptiles, may possibly prove to be mammals. The 

 difference between a cynodont reptile and a monotreme is less 

 than the difference between a monotreme and a marsupial, and 

 again is not much greater than that between a marsupial and an 

 insectivore. 



Very interesting is the information that has been recently 

 recorded with regard to the oldest known reptiles. Towards 

 the close of 1907 Dr. Thevenin, in the Annates des Paleontologie, 

 1907, pt. 3, p. 19, described from the uppermost Carboniferous 

 oil-shales of France certain remains which he named Sauravus 

 costci, and regarded as the oldest discovered reptile. He 

 considered it as being related to Palceohatteria and the other 

 Rhynchocephalia. According, however, to Dr. S. W. Williston 

 {Journ. Geol. vol. xvi. p. 395), it is much more probably akin to 

 Isodectes copei, an extremely primitive tetrapod from the Coal 



