IX.] OF THE DOG. 141 



so conspicuous a feature in this region of the skull, and 

 which are produced outwards into the lower wall of the 

 external auditory meatus (tarn}. In the antero-internal angle 

 of the bulla is seen the irregular orifice of the Eustachian 

 canal. Close to the inner side of this is an oval aperture 

 which is at the same time the anterior extremity of the carotid 

 canal and the entrance to the foramen lacerum medium (/////) 

 through which the internal carotid artery enters the cranial 

 cavity. In front, and rather to the outer side of this, is the 

 foramen ovale (fo) piercing the alisphenoid, and immediately 

 before this is a round aperture (as) leading to a short canal 

 running horizontally forwards through the same bone at the 

 root of its pterygoid process, and opening anteriorly into the 

 foramen rotundum (fr). Through this the external carotid 

 artery runs lor part of its course, and it has been called the 

 alisphenoid canal. * 



In front of the outer side of the auditory bulla' is the 

 glenoid fossa for the articulation of the mandible, bordered 

 behind by the conspicuous curved postglenoid process (.<?/). 

 Immediately behind this the root of the zygoma is pierced 

 by a large hole, postglcnoid foramen ( f>gf), through which a 

 vein passes out from the lateral sinus within. 



Behind the auditory bulla, to the inner side, is the large 

 foramen lacerum paste rius (///), and situated deeply within its 

 recesses, the posterior opening of the internal carotid canal. 

 On a ridge of the exoccipital, between this large foramen 

 and the depression immediately in front of the condyle, is 

 the small, nearly circular condy la r foramen (cf\ and at the 

 outer termination of the same ridge rises the conical paroc- 

 cipital process (//>), abutting at its base against the hinder 



1 See H. N. Turner's " Observations relating to some of the Foramina 

 in the Base of the Skull in Mammalia," &c., Proc. Zool. Soc. 1848, 

 p. 63. 



