514 



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



The epipterygoid is widened so as to form a long lateral 

 wall to the anterior part of the biain-case. It is produced 

 backward to articulate with the quadrate, and is supported by 

 a massive process arising from the anterior iace ot the par- 

 occipital process. The second and third divisions of the fifth 

 nerve leave the brain-cavity, which is here not homologous 



Fie:. 5. 



Thrinuxudon liorhinus, Seeley. Dorsal surface of the skull, chiefly from 

 the type-specimen, X 1. 



with that of a reptile but agrees with that of a mammal in 

 including the cavum epipterycum, through a single foramen 

 lying above the quadrate ramus of the epipterygoid. 



The pterygoid is a remarkable bone ; it is articulated with 

 the lower surface of the basip'eiygoid processes, and has a 



