MUE.^NOSAUEUS. 



83 



foramen {jug.). The posterior (exoccipital) edge of the combined bones is sharp; 

 the anterior (opisthotic) broad, ronnded, and concave from above downwards, the 

 upper end of the concavity being continued as a shallow groove {c.a.) on to the base 

 of tlie paroccipital process ; this groove no doubt marks the position of the columella 

 auris. On the inner face of the bone there is a small foramen (/.), probably for a 

 blood-vessel. 



The su2}raocci2ntal (text-fig. 45, A, B) is a short fl-shaped bone which enclosed the 



Text-fig. 45. 



nar.J. 



€XO.Oflf. 



exo. 



Z. 



Supraoccipital and exoccipital-opisthotic of Miircenosaurus durohrivensis : A, supraoceipital from behind ; 

 B, from right side ; C, exoceipital-opi.sthotic from front ; D, exoccipital-opisthotic from outer side ; 

 E, exoccipital-opisthotic from inner (cranial) side. (E. 2861, nat. size.) 



a., cavity for ampulla of posterior vertical semicircular canal ; loc.f., facet for basioccipital ; c.a., groove 

 for columella auris ; exo.o]).f., facet for exoccipital-opisthotic; /., foramen (? vascular) on inner face of 

 exoccipital ; A.c, channel for horizontal semicircular canal ; ^yVgr., jugular foramen ; op.g., groove marking 

 line of junction between the exoccipital and opisthotic elements ; par.f., facet for union with the 

 parietal ; pro.f., facet for pro-otic ; p.v.c, channel for posterior yertical semicircular canal ; q.f., facet for 

 quadrate;?-., ridge projecting into upper end of the foramen magnum; soc./., facet for su^jraoccipital ; 

 XII., foramina for the hypoglossal nerve. 



