28 ANATOMY OF A CHELONIAN. 



a process on the outside of the ramus, overlap- 

 ping the surangular. 



55. The bones of the skull, seen in their natural rela- 

 tive positions from the interior of the cranial cavity, 

 may be studied either on one-half of a prepared median 

 dorso-ventral section of the cranium, or, better, on a 

 recent specimen prepared by the student ; as the carti- 

 laginous parts, which are important, are apt to be re- 

 moved unless special care has been taken in preparing 

 the specimen. 



56. On the Interior of the Skull, as viewed from one 

 side, note : 



a. The basi-occipital bone, divided by the saw in the 

 median line behind. 



b. External to the basi-occipital, the exoccipital. 

 having in it the foramen (25, b) for the twelfth 

 cranial nerve ; between it and the basi-occi- 

 pital another foramen ; and between it and the 

 opisthotic the foramen of exit for the vagus 

 and spinal accessory nerves (25, c). 



c. Above the exoccipital the large supra-occipital, 

 with its spine. 



d. On the base of the skull, and in front of the 

 basi-occipital, the divided basi-sphenoid, with its 

 median ridge and one of the clinoid processes 

 described above (43); and in front of the cli- 

 noid process a hollow from which some mus- 

 cles of the eyeball (184) arise. 



e. External and dorsal to the outer edge of the 

 posterior portion of the basi-sphenoid is a car- 

 tilaginous plate (already removed if care has 



