120 SECTION OF THE MASTODON HEAD. 



conspicuous. At the most posterior part of the cerebral cavity is seen the 

 great occipital opening, the vertical diameter of which is just half that of 

 the vertical diameter of the brain. This cavity for containing the cerebrum 

 is remarkably protected by surrounding parts.; superiorly it is guarded by 

 the great number of diploic cells which occupy the vertical region ; pos- 

 teriorly, by a few cells, principally by the vast mass of cervical muscles ; 

 anteriorly and inferiorly, by the base of the cranium. 



.SECTION OF THE FACE. 



This section on the right side exhibits above and behind the septum 



narium ; below, part of the nasal and the guttural surfaces. The upper 



part of the septum is formed by the nasal plate of the os ethmoides, which 



is five inches long above, and . nearly six inches at the lower edge. This 



lower edge is curvilinear, and terminates in a posterior edge, which unites 



the posterior extremities of the two lines mentioned, and is itself three 



inches long. The inferior edge of the latter is united with the superior 



edge of the vomer by a suture, the relics of which are quite visible. * The 



superior edge is attached to the base of the cranium ; the posterior to the 



ethmoidal cells ; the anterior is free, and corresponds with the cavity of 



the nostrils. Below and in front of the nasal plate of the os ethmoides is 



seen the vomer. This bone is of a triangular form. Of its three edges, 



the posterior superior corresponds with the inferior edge of the nasal plate. 



The anterior edge is connected with the intermaxillary bone, and the inferior 



edge is free between the guttural and nasal fossos. Each of the edges 



measures about five inches in length. The thickness of the vomer is about 



the twentieth of an inch ; at its middle part, on removing the vomer, we 



