426 



Mr. II. Day on the 



slightly dumb-bell shaped in form — broad-based, then con- 

 stricting, to expand again and end in what appears to be 

 definite articulating facets. These anterior processes, 

 which are stout flattened rod-like structures, are to be 

 regarded as " basipterygoid " processes, and are of great 

 interest on account of their articulating facets, the interest 

 of which will be apparent when we come to deal with the 

 homologies of this bone. 



Fiar. 



Cast of the dorsal surface of the compound para-basisphenoid bone of 

 Rhadinkhthi/s monensis showing the well-defined pituitary region. 

 (Specimen C.) X 76 diams. No. L 10822. M. M. 



The posterior pair of lateral processes are flat thin flanges 

 of bone which project outwards and backwards, and possess 

 on their surface a few indefinite ridges. 



This completes the account of the dorsal and ventral views 

 of the bone, but a few remarks may be added on specimen C 

 This is an almost complete cast of the dorsal surface of the 

 bone, only a few small fragments of actual bony material 

 being still adherent. The dorsal surface has already been 



