300 STRUCTUltE OF THE SHEEP. 



to afford more room for the development of the temporal 

 muscle, which governs the jaw, than is required for the more 

 moderate exertions of herbivorous animals. The petrous 

 portion of the temporal bone, so called from its rocky nature, 

 is apparently a solid convex figure. It contains, however, 

 the organ ol" hearing, and has on its internal surface orifices 

 for the passage of the auditory nerve, and on the external we 

 fmd a larger orifice for the passage of sound. The internal 

 structure of this bone is as beautiful as it is curious, possess- 

 ing vestibules and canals for the ramification of the nerve, 

 and a singular cavity having a communication with the mouth, 

 in which are discovered four diminutive bones, with their 

 corresponding muscles, which serve the purpose of propaga- 

 ting and modifying the sound. 



The inferior and middle parts of the cranium are formed 

 principally by the sphenoid, a bone which somewhat resem- 

 bles a bird in flight, having a bod}' and four processes, two 

 of which are called the wings and two the legs. This bone 

 supports the middle lobes of the cerebrum, and presents 

 holes and depressions for the passage of nerves. The cranial 

 cavity is separated from the nasal by the ethmoid bone, which 

 also somewhat resembles a bird in flight, but without legs, 

 and is situated in front of the bone last described. It sup- 

 ports the anterior lobes of the cerebrum, and has holes for 

 the exit of the olfactory nerves ; and on its internal and in- 

 ferior surface it forms cavities called the ethmoidal sinuses, 

 which are separated by a long septum from each other, and 

 are perforated by a vast number of small holes for the passage 

 of the olfactory nerves to the nasal cavities. It is this thin 

 part of the bone which is penetrated in the operation of 

 wiring giddy sheep. Such is a brief description of the 

 various bones which form the cranium and envelop the brain, 

 and which are connected together and arranged on principles 

 more durable and economical than can be displayed by the 

 noblest specimens of mechanical skill. 



The face occupies a larger portion of the head than the 

 cranium, but is less in proportion than the ox and the horse, 

 and particularly the latter animal. Its upper part is formed 

 by the lower portion of i\ie frontal hones, which are consid- 

 erably longer in the sheep than in the horse, descending 

 much lower down, and in fact forming the roof of a great 

 portion of the nasal cavity. Another peculiarity in these 

 bones is, that whereas in the horse they descend in a straight 



