Mr. D. M. S. Watson on the Cynodontia. 



511 



Brain-cane. — The brain-case is still incompletely exposed, 

 but it is obvious that the structure is very much as in 

 GomphognathuSj there being a much expanded epipterygoid 

 with a venous groove along the suture between that bone and 

 the parietal and a foramen opening into it. 



The stapes is a short, bone, very nearly as wide as long. 

 It is perforated dorso-ventrally by a large foramen. 



Except for one detail, the dentition was correctly described 

 by Owen, the dental formula is ^'. -*, c. -*, m. ^. There is no 

 visible distinction of premolars and molars and no evidence of 

 any kind of tooth-succession. Although Owen states that 

 the molars are " simple crowned " and conical, there is clear 

 evidence, chiefly from the impression on the matrix, that they 

 are flattened, being oval in cross-section, with the long axis 

 antero-posterior ; and cusped, the anterior cusp being the 

 main cone, and being followed by one or two smaller subsidiary 

 cusps. 



The upper canine is a tooth of extraordinary antero- 

 posterior width. 



Cynosuchus supportus, Owen, Cat. Foss. Rept. S. Afr. 

 pi. xvii. 



Type, Brit. Mus. Nat. Hist. Ctsticephalus-zone, Styl- 

 krantz, Sneewberg. The snout slightly dorso-ventrally 

 crushed and broken, but well preserved. 



Fiar. 4. 



Mx. Nfl. S.Mx. 



i i \ \ jfltf. f ''///. '(tit 



Cynosuchus supportus, 0\v. The left side of the snout of the type, X 1. 



35* 



