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 



enjtt. 



Fio. 238. 



Amia calva, L. A, ventral view of skull and upper jaw. B, posterior view of skull, an, 

 articular surface of quadrate, ap, of symplectic ; bo, basioccipital ; enpt, entopterygoid ; tp, 

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

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

 o.c, occipital cartilage ; op, opisthotic ; p and pa, palatine bones ; pm, premaxilla ; po t pro- 

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

 v/, 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 



