IX.] OF THE DOG. 121 



ately 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 (/;-). Through this the external 

 carotid artery runs for 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 cnxw^d postgienoid process {gp). 

 Immediately behind this the root of the zygoma is pierced 

 by a large ho\Q, postgknoid fo?-a?fie/i {pgf), through which a 

 vein passes out from the lateral sinus within. 



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

 foramen lacerum posterius {flp), 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 condylar foramen (cf), and at the 

 outer termination of the same ridge rises the conical paroc- 

 cipital process {pp), abutting at its base against the hinder 

 end of the auditory bulla. Immediately behind the bulla, 

 and to the outer side of the abutment of the paroccipital 

 process against it, is an oval hole {sm), partially divided by 

 a constriction into an inner and an outer division. In 

 the inner division the end of a small cylindrical plug of 

 bone, the tympanohyal, can generally be seen. The outer 

 division is the stylomastoid foramen, through which the 

 seventh nerve, or portio dura, makes its exit. The bone 

 forming its outer boundary is the mastoid portion of the 

 periotic. 



^ 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. 



