332 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



ossifications. In Birds these fuse with one another 

 and with the supra- and ex-occipital bones to an 



Fig. 140. Diagram of the Cranial Bones of a Mammal, showing the 

 Foramina of exit of the several Cerebral Nerves.* 



1, Olfactory nerve ; 2, optic ; of, optic foramen ; da, foramen lacerum anterium, for 

 the passage of the third, fourth, sixth, and first branch of fifth ne r \ r e (3, 4, 

 6, 5<x; ; fr, foramen rotundum, for the second branch of the fifth (5)3) ; fo, 

 foramen ovale, for the third branch of the fifth (ay") ; am/, stylomastoid 



foramen for the seventh nerve (7) ; flp, foramen lacerum posterius, for the 

 ninth, tenth, and eleventh nerves ; MES, mesethmoid ; cf, condylar foramen 

 for the twelfth nerve ; CP, cribriform plate : PS, presphenold ; BS, basi- 



sphenoid; BO, basioccipital ; os, orbitosphenoid ; AS, aiisphenoid ; E'O, ex- 

 occipital ; PEE, periotic ; F, frontals ; PA, parietals ; so, supraoccipital. 



extent of completeness which is greater than ordinarily 

 obtains among Mammals. 



In addition to the important relations which the 

 cranium bears to the sense capsules, it has others even 



* This diagram was, many years ago, shown to the author by 

 Prof. Flower, F.R.S., and it is here, for the first time, published 

 by his kind permission. 



