W. H. TWELVETREES OIT A NEW THEEIODONT EEPTILE. 543 



and the absence of the well-marked club-shaped outline characterizing 

 the crowns of teeth of Rhopalodon, Pischer, are the reasons which 

 have mainly influenced me in keeping it apart from that genus. In 

 Ehojocdodon, too, I have noticed a greater smoothness and more finely 

 marked superficies of enamel. Venturing thus to distinguish it 

 generically, and necessarily specifically, I submit the name of Clio- 

 rhizodon orenburgensis, in allusion to its contracting roots terminating 

 in closed sockets, and to the government in Eussia in which it was 

 found. 



Discussio]sr. 



Prof. EuPEET Jones referred to the finding of reptilian, remains 

 in the dolomitic conglomerate of Bristol. It had been asserted that 

 continental beds with similar reptiles were Permian, while it was 

 now known that the former were Triassic; and he thought it 

 should not be too hastily assumed that these Russian beds were 

 Permian. 



Prof. BoTD Dawkins said that the great feature of the Secondary 

 rocks was the evolution of the Eeptilia. The discovery, then, of so 

 highly organized a group as Theriodonts was rather a reason for 

 regarding these rocks as Secondary. 



Prof. Seelet said he really did not know what a Theriodont was, 

 and did not believe that, as a division of the Eeptilia, the Therio- 

 dontia had any existence. What the specimen on the table was he 

 could not say ; and he did not think it was perfect enough for 

 description. 



Mr. HuLKE thought the specimen too obscure for forming an 

 opinion at once. He concurred with Prof. Seeley's remarks as 

 to the dubious value of the Theriodontia as a natural family of 

 reptiles. When the subject was some time since brought before the 

 Society by Prof. Owen, he had stated that even teeth of the Iguano- 

 don present characteristics supjjosed to be Theriodont. 



The Peesident said the teeth of these so-called Theriodonts were 

 very difi'erent from those of the Thecodontosaurus and Palceosaurus 

 of the Bristol conglomerate ; but it was doubtful what was the true 

 age of these so-called Permians. 



