36 CERVICAL VERTEBRA?. [chap. 



In the Elephant (order Proboscidea), the atlas mud 

 resembles the human atlas. The axis has a short conic 

 odontoid process, a very massive spine, broad above and bifu 

 posteriorly. The bodies of the other vertebrae are very shoi 

 flattened, sub-circular disks, very slightly opisthoccelous 

 Excepting the seventh they all have short spinous processes 

 and short, broad, and largely perforated transverse processc- 

 The seventh has a high spine, an imperforate transverse pn 

 cess, and on the hinder edge of its body a very distinct art 

 cular cavity for the head of the first rib. In the young animj 

 this is divided into two equal parts by the neurocentr 

 suture. 



In the order Sirenta, the Dugong (Hali'core) has sever 

 cervical vertebrae, as in the Mammalia generally. The atlas 

 has short imperforate conical transverse processes. The axis 

 has a high arch and massive neural spine, a short rounded 

 odontoid process, and very rudimentary transverse processes. 

 The others have short and wide bodies, small spines, and 

 irregularly developed transverse processes, often not com- 

 pletely enclosing a vertebrarterial canal. 



The Rhytina, a large animal of this order, which became 

 extinct towards the close of last century, had also seven 

 cervical vertebrae, and the Miocene Halitherium had the 

 same number. 



The Manatis (genus Ma?ialus), of which there are two 

 well-marked species, one inhabiting the west coast of 

 Africa, and the other the east coast of Central and South 

 f America, never have more than six vertebrae in the cervical 

 region. These resemble generally those of the Dugong, 

 having short and wide bodies, and very irregular transverse 

 processes. In a specimen of M. senegalcnsis, in the 

 Museum of the College of Surgeons, the second and third 

 are ankylosed by their bodies, and the neural arches of most 



