80 



MAllINE EEPTILES OF THE OXFOED CLAY. 



cartilage. lu front of this region is the deeply concave pituitary fossa. The sides 

 of the bone are fiat and roughened posteriorly, and bear deep grooves running 

 downwards and forwards from the upper posterior angles and terminating in the large 

 paired foramina (i.e./.), by which the internal carotids enter the pituitary fossa. 

 Above these foramina tlie sides of the bone are produced outwards and forwards 



Basioccipitiil, exoccipital-opistliotic, basisphenoid, and part of parasphenoid of Munenosaiinis leedsi: 

 A, from side; B, from below. (R. 2422, nat. size.) 

 lis., basisphenoid : ex.of)., united exoecipital and opisthotic ; i.c.f., internal carotid foramen ; oc.c, occipital 

 condyle ; iws., parasphenoid ; p.p., paroccipital process ; pt.f., pterygoid facet ; soc.f., facet for 

 supraoccipital ; v.c.p., lower cylindrical processes of basisphenoid. 



into a pair of processes bearing at their extremities facets, presumably for union 

 with the pterygoids. The ventral surface is much roughened posteriorly, but for 

 the greater part of its extent it is concealed by the closely adherent hinder end 

 of the parasphenoid [])as.). The posterior border of this is sometimes notched in 



