58 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 3, 



are very broad plates, separating the large anterior palatine fora- 

 mina (a) from the comparatively small posterior nares (b), which are 

 round apertures, 1 inch in diameter, and 5 inches from the anterior 

 end of the snout, situated between the vomer, the maxilla, and the 

 palatine bones on each side. The vomers unite in the middle line 

 with one another and with the prolonged anterior extremity of the 

 basisphenoid. Posteriorly they are connected with the palato-ptery- 

 goid arcade, the separate components of which cannot be accurately 

 denned. The palatine portion, however, is a broad, flat plate, measur- 

 ing 3*5 inches between the posterior nares and the palato-temporal 

 foramen. It is united externally with the maxilla. Internally it 

 is separated by a narrow interval from the basisphenoid. Posteriorly 

 it passes into the pterygoid portion, which is narrow and curves out- 

 ward, beneath the inner contour of the temporal prolongation of the 

 skull, to be lost about the posterior and internal angle of that region. 

 Externally the margin of the pterygoid portion is arcuated, to form 

 the boundary of the palato-temporal foramen. Through this fora- 

 men the under surface of the upper wall of the skull in the temporal 

 region becomes visible. The sutures separating the component bones 

 of this region are not visible ; but on the level of the posterior end 

 of the basisphenoid it presents an elongated aperture, or supratem- 

 poral foramen (c), 1*3 inch long by 0-4 inch wide. The long axis of 

 this foramen is directed obliquely forwards and inwards, and it is 

 nearer the pterygoid than the external boundary of the palato-tem- 

 poral foramen. 



Although I worked out this region of the skull with extreme care, I 

 was in doubt whether the aperture in question was really a natural 

 one, until I cleared away the matrix from the opposite side, and 

 there found a foramen of quite a similar character, though distorted 

 by the crushing of this part of the skull. 



The premaxillary bones, strong and arched, send back two pro- 

 cesses from their apposed ends, which run upwards and backwards 

 in the middle line (in the manner common in Amphibia) towards the 

 junction of the vomers. As the anterior portion of the vomerine 

 plate is inclined upwards and forwards, it follows that the most 

 anterior region of the palate has a somewhat arched roof, as in the 

 Frog. The anterior palatine foramina (a), included between the 

 recurrent processes of the premaxillaries, their dentigerous processes, 

 and the vomers, appear to be about 1| inch long by 1 inch wide ; but 

 it is difficult, from the condition of the fossil, to define their limits 

 with exactitude. 



Thirty-seven teeth, or remains of teeth, are visible. Of these, on 

 the left side, thirteen are situated in the premaxilla and maxilla, and 

 three on the palatine bone ; while, on the right side, nineteen are 

 attached to the premaxilla and maxilla, one to the vomer, and one to 

 the palatine bone. On the whole, the maxillary teeth decrease in 

 size from before backwards, but not very regularly. The first tooth 

 on the left side was 1*7 inch long when entire, by about half an 

 inch thick at the base. The second immediately follows it, and is 

 somewhat larger. The third, of about the same size as the second, 



