262 Mr. E. I. Pocock on the 



posterior orifice between the periotic and the basioccipital. 

 Posteriorly the canal lies between the tympanic bulla and 

 the periotic. Anteriorly it is a tube in the tympanic itself, 

 and its anterior orifice opens at the antero-internal angle of 

 the bulla on the admedian side of the adjacent orifice of the 

 eustachian tube, and just above the foramen lacerum medium, 

 the anterior space between the periotic and the basisphenoid, 

 through which the artery, after leaving the canal, enters the 

 cranium. 



Except that the posterior orifice of the canal is always 

 situated further forwards and that the anterior orifice, even 

 Avhen the canal is complete, opens into a space beneath the 

 bulla common to it and the eustachian tube, the arrangement 

 found in the Viverrid?e does not diflier much from that of 

 the Canidse. But within the Viverridse there are some 

 interesting variations in detail worth putting on record. 



The facts observed in most of the dominant types may be 

 described before a general summary is attempted. 



In an example of the African civet {Civettictis civetta) 

 the posterior orifice of the carotid canal is situated about 

 halfway along the inner wall of the bulla further in advance 

 of the foramen lacerum posticum than in the Felidse and 

 Canidie. Tliroaghout its lengtli it is an open channel, and 

 not a closed tube. It passes nearly vertically between the 

 tympanic and the adjacent edge of tlie basioccipital. It 

 then turns, and ceases at the edge of the inturned tympanic. 

 Thence tbe artery runs forwards beneath the anterior part 

 of the tympanic, and enters the foramen lacerum medium^ 

 which forms a small semicircular notch in the basisphenoid 

 and is just visible at the antero-internal angle of the bulla 

 when the skull is viewed from below, although it is partially 

 overlapped by a small bridge of bone jutting iuAvards from 

 the bulla to the antero-lateral angle of the basioccipital. 

 Behind this bridge the periotic appears for a small space on 

 the surface of the skull between the bulla and the basi- 

 occipital. 



In examples of the Oriental civets {Viverra zibetha, V. 

 tangaluyiga, and Viverricula malaccensis) the arrangement is 

 similar in all essential respects, except that the periotic does 

 not reach the surface of the basis cranii, the foramen lacerum 

 posticum is usually narrow, and the foramen lacerum medium 

 much deeper and more apparent on the base of the skull*. 



* In properly cleaned skulls a bristle can be passed throug-h the carotid 

 canal from back to front when the canal is tolerably straight ; but where 

 it makes a sharp bend, as in the African civet examined, this cannot be 

 done. 



