540 



W. H. TWELVETREES ON A NEW THEKIODONT REPTILE. 



38. On a new Theeiobont Eeptile (Clioehizodon oeenbtjegesnis, 

 Twelvetr.) from the Upper Permian Cupriferous Sandstones of 

 Kargalinsk, near Orenburg in South-eastern Eussia. By W. 

 H. TwELVETREEs, Esq., F.L.S., P.G.S. (Eead April 14, 1880.) 



The fossil to be described in this paper was found, in the summer of 

 1879, in the copper-mine of Eoshdestvensk, about thirty miles N". 

 of the town of Orenberg. The mine forms one of several groups 

 known collectively as the mines of Kargalinsk. The steppe in 

 which it is situate is composed of Upper Permian beds of marl 

 and sandstones resting upon limestone containing Zechstein fossils. 

 Copper-mines in this steppe have been worked from time immemorial. 

 Organic remains are only found in the runs of copper-ore and 

 are everywhere absent from the bare sandstones. I have resided 

 several years in the neighbourhood and am acquainted only with 

 the following : — 



Calamites 



Lepidodendron. 



Leaves of Aroides crassispatha, 



Kutorga. 

 Conifer trunks and twigs. 

 Unio, sp., allied to U. umho7mtus, 



Fischer. 



Amhlypterus, sp. 



Flatysomus, sp. 



Eemains of Labyrinthodonts. 



Remains of Saurians iindetermined, 

 including Ehopalodoji, Fischer, 

 and Leuterosaurus, Eichwald. 



Description. 



The fragment under consideration is a portion of a reptilian jaw*, 

 apparently comprising parts of the maxillary and premaxillary 

 bones. When it first came into my possession it only presented to 

 view vertical sections of the roots of the canine and molars split 

 down longitudinally. Experimental chiselling disclosed the fine 

 canine crown (c), besides the crown of an incisor (^) and crowns 

 of two of the molars (m 5 & 6) . The form and implantation of 

 the roots had already led me to the conclusion that the animal 

 belonged to the Theriodont order ; and this inference was confirmed 

 by the appearance of the canine and incisor crowns. 



Between the canine and incisor is a diastema or toothless interval 

 of '37 inch. The latter slants backwards and outwards. Its crown 

 is of a triangular form, and I am unable to detect any trace of ser- 

 ration ; though it must be confessed that the anterior edge is not 

 quite in a state to admit of a positive assertion. The tooth is not 

 susceptible of further development from the matrix without risk of 

 injury to the canine. 



* Kindly given to me by Mr. Thos. Eickard, who has for several years 

 studied the geology of the Kargalinsk strata and the conditions of the copper 

 in their rocks. 



