W. H. TWELYETBEES 0¥ A NEW THEEIODONT REPTILE. 



541 



Portion of Upjper Jem (right side) of Cliorhizodon orenbur 

 gensis, Twelvetrees, Nat. size. 



i. Incisor. 



c. Canine. 



m 



m 1-10. Molars. 



Proceeding to the canine a fine recurved tooth is exhibited (c). 

 It is thickest at the base of the crown and somewhat compressed 

 laterally, though less so than the canines of any other Theriodonts 

 that I have seen. Its posterior edge bears no sign of serration or 

 crenulation. The interior is too minerahzed to show reliably details 

 of structure. Its exterior is faintly marked longitudinally. The 

 root not being split quite in the median plane, the pulp -cavity is not 

 displayed ; but the form of the socket and of the implanted fang is 

 instructively shown. The former is a cavity slightly narrowing 

 towards its closed termination, and the root follows the same shape. 

 The significance of such mode of implantation has been finely shown 

 by Prof. Owen in his description of fragmentary indications of a 

 huge kind of Theriodont reptile (Titanosuchus ferox, Ow.) from the 

 Cape of Good Hope*. The present fossil is a remarkably good illus- 

 tration of the views propounded in that memoir, and I am greatly 

 indebted to its illustrious author for the guidance thereby afi'orded 

 me. Not only the canine, but the molars too, which differ from the 



* Quart. Jouru. Geol. Soc. vol. xxxv. May 1879, pp. 189 et seg^. 



