402 Mr. Yarrell on the Osteologi/ of the Fennec. 



the upper edge of the temporal muscle so conspicuous in the Cam's 

 Lupus and Lycaon^ Vulpes and lagopus. There is a greater de- 

 velopement pf the lateral porlions of the parietal bones by which 

 it obtains a larger volume of brain ; the zygomatic arch is more 

 compressed, and the post orbital portion of the bones forming the 

 arch is much weaker. 



The head compared with those of the most perfect English breed 

 of dogs more closely resembles that of the Terrier^ the Canis Bri- 

 tannicus of authors,* than any other, but the muzzle in the Fennec 

 is more pointed. The form of the lower jaw and its condyles also 

 agrees precisely with the same parts in the dog. 



The head of the Fennec however presents another peculiarity 

 which must not be omitted; the auditory cells in this little animal 

 are even larger than the same parts in our common Fox^ although 

 the Fennec is two-thirds less than the Fox in size. The external 

 conch is also as large in proportion as these cells, and judging by 

 analogy it is probable that the Fennec possesses the sense of hear- 

 ing to an extent far beyond that of most other quadrupeds. 



To render this more evident, some further explanation may be 

 necessary. The most perfect organs of hearing may be described 

 as composed of three distinct portions, each portion containing 

 several separate parts. 



The first, external, consisting of the conch, the canal, and the 

 membrana tympani ; the third, internal, containing the vestibulum, 

 semicircular canals, cochlea, &c. -, the second part, intermediate 

 in situation, and connecting the first and third portions, consists 

 of the ossicula auditus, a connected series of fourf very small and 

 beautifully formed bones, which by their power of communication 

 transfer the external impressions received upon the membrane of 

 the tympanum to the internal cells partly occupied by portions 

 of the auditory nerve. 



In quadrupeds generally, the auditory cells are enlarged when' 

 the external conch is small, and vice versa, as the crania of the 

 Weasel tribe will shew, when compared with those of hares and 



* The Canis terrarius of Dr. Cains, so called from the eagerness with which 

 this species goes to earth. 



+ Called the malleus, incus, os orbiculare and stapes. 



