MORPHOLOGICAL REVISION 



107 



shared by all the postorbital bones, no horns or processes being developed. 

 The otic notches are very slightly developed, but the quadrate region extends 

 quite a little posterior to the occipital condyle. The sutures of the skull 

 are known only imperfectly; in specimen No. 4557 the sutures can be made 

 out as far as shown in fig. 36 b. The orbits are relatively small and nearly 

 circular, and are situated in the anterior third of the skull. They are, with 

 the nares, entirely superior in position. The nares are not terminal. On 



Fig. ^6.—Trimfrorhachis insignis. No. 4557 Am. Mus. 



A. Top view of a skull. X |. 



B. Another skull carrying same number as that shown in A, showing such sutures as 



can be made out. X |. Lettering as usual. 



C. Lower view of same skull shown in B. X |. pt, pterygoid. 



D. Lower surface of skull shown in A. X yi. pt, pterygoid; pa, parasphenoid. 



the lower surface the elongate parasphenoid joins a well-formed basioccipi- 

 tal, which bears a single, oval occipital condyle with a concave, articular 

 face. The pterygoids send processes inwards to join the parasphenoid, and 

 backward to the quadrate region. The anterior processes of the pterygoid 

 are very narrow, with concave inner edges, leaving very large palatal vacui- 

 ties. The posterior portion of parasphenoid and the pterygoids are covered 

 with fine teeth. 



In two specimens, considered by Cope as T. insignis, there is consider- 

 able difference in the parasphenoid and basioccipital bones. In No. 4565, 



