Professor H. G. Seeley — Dentition of Cynognathus. 487 



from the flat maxillary bones of the palate by vertical sutures. It 

 appears to afford evidence that the premaxillary bones enter into the 

 front of the hard palate, and are free from palatal teeth. The skull 

 of C. platyceps (op. cit., fig. 30, p. 139) adds nothing to our knowledge 

 of the anterior part of the palate. Only the posterior part of the 

 median suture is exposed, dividing the concave channel of the hard 

 palate. There are no indications of palatal teeth ; but this is no 

 evidence that such teeth did not exist, for such structures are not 

 likely to be found unless there is reason to look for them, and they 

 would be easily removed by the chisel without detection. 



I am indebted to the generous co-operation and enthusiasm of 

 Dr. D, R. Kannemeyer for a fragment of a right maxillary bone from 

 Wonderboom, which has almost exactly the size, form, and aspect of 

 the corresponding region of the jaw of Cynognathus crateronotus. 

 I have removed the matrix in the Geological Laboratory of King's 

 College, London ; and the bone (Plate XXIV) shows both externally 

 (Fig. 2) and on the palate (Fig. 1) characteristics seen in no other 

 figured example, but confirmed by other evidence in my hands. 



The maxillary bone is separated by sutures of a squamose type 

 from the nasal bones above and the premaxillaiy bones in front. The 

 vertical premaxillary sutural surface is l-i~o-inch deep, flattened, -j^rinch 

 wide, and is limited posteriorly by the large cavity for the mandibular 

 canine, which is excavated in the skull for 1^ inch, and made partly 

 by the maxillary, partly by the premaxillary bone. 



Above the premaxillary suture in front is a small, smooth, rounded 

 notch, which appears to be the hinder angle of the anterior narine, 

 between the premaxillary and nasal bones. 



The maxillary bone is limited at the upper border by the strong, 

 vertical, squamous suture with the nasal bone. This sutural surface 

 seen on the inner aspect of the specimen is half an inch deep in front, 

 with the depth increasing as it extends backward. The curved contour- 

 line of junction is indicated by the maxillary bone being 2 inches deep 

 in front and about 3^ inches in depth at the vertical fracture behind. 



Externally (PI. XXIV, Fig. 2) the anterior and larger part of the 

 bone is convex, both from front to back and from above downward. 

 This convexity is only modified by a slight, shallow, wide, longitudinal 

 concavity, extending backward from below the nasal suture towards 

 the direction of the prefrontal bone. But inferiorly the bone contracts 

 in width behind the canine tooth, defining the bulbous snout, so that 

 the lower and hinder external surface is concave. 



The alveolar border behind the canine tooth, seen from the side, 

 is straight or concave in length, while in front it recedes laterally 

 upward towards the premaxillary suture, being convex above the 

 maxillary canine and concave in front of the mandibular canine. 



The posterior fracture passes through a conspicuous, circular, pre- 

 orbital pit in the middle depth of the bone, situated above the 

 fourth or fifth molar tooth. It corresponds in position exactly with 

 the sub-orbital or middle foramen seen in the maxillary bone of the 

 type-specimen of Cynognathus crateronotus (op. cit., p. 72, fig. 5). 

 Now that the matrix is removed (PI. XXIV, Fig. 2), the fossil shows 

 externally at -rV inch above the alveolar border a linear succession 



