SKULL 



269 



(p. 11). Generally, it has a concave posterior face, just like that 

 of a centrum, to which the vertebral column is attached without 

 distinct articulation. Paired basisphenoids appear in the region of 



- enpt. 



Fig. 238. 



Amia calva, L. A, ventral view of skull and upper jaw. 13, posterior view of skull, aa, 

 articular surface of quadrate, op, of symplectic ; bo, basioccipital ; enpt, entopterygoid ; ep, 

 epiotic ; ept, ectopterygoid ; ex, exoccipital ; /, posterior temporal fossa ; h, hyomandibular ; 

 tnp, metapterygoid ; mx, maxilla : n.a, neural arch, whose centrum is fused to basioccipital ; 

 o.c, occipital cartilage ; op, opisthotie ; p and pa, palatine bones ; 33m, premaxilla ; po, pro- 

 otic ; pp, supratemporal ; pr, parasphenoid ; pt, post - temporal ; sq, pterotic ; v, vomer; 

 c./, vagus foramen. 



the pituitary fossa, and may fuse to a median bone. The lateral 

 wall of the brain-case between the orbits is strengthened by an 

 alisphenoid in the region of the trigeminal foramen, and by an 

 orbitosphenoid near the optic foramen. The antorbital cartilage 



