100 ANATOMICAL STEUCTUEE OF THE SHEEP. 



sphenoid, ethmoid, occipital. The frontal bones form the an- 

 terior part between the eyes, called the forehead. The inner 

 plate of these bones is separated from the outer, forming a 

 ca^-ity between them called the frontal sinus, which sinus is 

 divided by a septtim or ridge to afford support and strength to 

 the part. 



The internal plate covers the anterior portion of the part 

 of the brain called the cerebrum. In horned sheep this frontal 

 sinus or cavity is considerably deeper than in others, affording 

 greater protection for the brain, the horned sheep being naturally 

 more pugnacious than its hornless brother, and with greater ad- 

 vantages to do harm. In horned sheep the horns proceed on 

 each side from the frontal bone, appearing to be prolongations 

 of that bone. The two parietal bones are placed at the upper 

 and middle part of the cranium, covering the middle parts, or 

 lobes of the cerebellum, their internal surfaces closely corres- 

 ponding to the external conformation of the cerebellum. 



The occipital bone is situated at the back or base of the 

 skull. It is a single bone possessed of great strength. Its in- 

 ternal surface covers the base of the brain called tlie cerebrum, 

 the medulla oblongata, which may be classed as the connection 

 between the brain and spinal cord, resting on its floor; the pos- 

 terior part of the bone is smooth and round, to articulate with 

 the first bone of the cervical vertebrae or neck, called the atlas. 

 It has many external projections for the attachment of muscle 

 tendons, giving motion of the head on the neck. 



The temporal bones forming the sides of the cranium are 

 composed of two parts, one the squamous temporal and the 

 other the petrous temporal, which in the sheep are distinct and 

 separate from each other. 



The squamous temporal is externally a convex plate, with a 

 hooked projection arising from it. This projection assists in 

 forming what is called the zygomatic arch. The squamoixs 



