PROF. OWEN ON THE ORDER THERIODONTIA. 



261 



19. On tlie Order Theriodontia, ivith a Description of a new Genus 

 and Species (^Elerosaeres * feeines, Ow.). By Prof. Owen, 

 C.B., F.R.S., F.G.S. (Read March 9, 1881). 



[Plate IX.] 



Or Permian and Triassic Reptilia the most interesting, those that 

 help to fill the hiatus separating the mammalian Marsupials from 

 the cold-blooded Vertebrates, seem to me to be the extinct species 

 constituting, or referable to, the Order Theriodontia. 



To the characters of this Order given in my ' Catalogue of the 

 Fossil Eeptilia of South Africa 'f, viz. "Dentition of the Carnivorous 

 type, incisors defined by position and divided from molars by a large 

 laniariform canine on each side of both upper and lower jaws," may 

 now be added " dentition ' monoplryodont' " %. At least I have not 

 had evidence of an immature specimen showing a milk-series of 

 teeth to be succeeded by a permanent series ; but if such should be 

 found in any of the extinct Eeptiles of the present Order, such Order 

 will be " Diphyodont," like the Mammalian Carnivora ; for there is 

 no evidence of any third set of teeth 'to follow those which may have 

 been preceded (though I doubt it) by a first or deciduous set. Of 

 the adult dentition, whether it be 6 ' first " or " second," the molars, 

 as a rule, are inferior in size to the incisors, as both are markedly 

 less than the canines. Add to these characters, " humerus perfo- 

 rated by an entepicondylar foramen "§. 



The Reptiles so distinguished or characterized are already refer- 

 able to several genera ; and although I fully recognize the artificial 

 character of a more or less forward extension of the ossified " septum 

 narium," there was a convenience in disparting the Theriodont 

 genera known in 1876 into " Mononarialia " and "Binarialia"||. 



At that date the " Mononarials " included Cynodraco %, Cyno- 

 champsa **, Oynosuchus ft, Galesaurus ±t, Nyihosaurus §§, Sccdopo- 

 saurus || ||, Procolophon ^[^[ : the "Binarials" included Lycosaurus *** 

 and Tigrisuchusfff. Gorgonops %%% manifested a third narial 

 modification. 



To this series have since been added species referable to some of 

 the foregoing genera, and, also to a genus Titanosuchus §§§. The 

 latter was founded on fragmentary fossils not yielding a narial cha- 



* Gr. a'iXovpo?, cat ; aavpos, lizard. t 4to, 1876, p. 15. 



t Anatomy of Vertebrates, 8vo, 1866, vol. ii, p. 268. 



§ lb. p. 19, pi. xix. figs. 2 & 3 k, h ; Quart. Journ. Geol Soc. August 1876, 

 p. 361, cut, fig. 2, k. 



|| Catalogue, ut supra, pp. 15, 17. 1[ Ibid. p. 19. 



** Quart, Journ. Geol. Soc. vol. svi. 1860, p. 61, pi. iii. 

 tt Catalogue, ut supra, p. 21. 



X\ Quart. Journ. Geol. Soc. vol. xvi. 1860, p. 58, pi. ii. 

 §§ Catalogue, ut supra, p. 24. || || Ibid. p. 24. %*f Ibid. p. 25. 



*** Ibid. p. 15. ttt Ibid. p. 17. ttl P- -7. 



§§§ Quart. Journ. Geol. Soc. vol. xxxv. 1879, p. 189, pi. xi. 

 Q. J. Gr. S. ]S T o. 146. T 



