HIPPOPOTAMUS. 



17 



c. Thk Vertebral Column. (Text-figures 2-7.) 



Cervical Vertebrae. — The atlas (Text-fig. 2, a, b) has a very large articulating 

 surface for the axis and broad transverse processes thickened at their distal ends. 



The axis (Text-fig. 2, c) has a blunt odontoid process and a very large articulating 

 surface for the atlas. The neural spine varies considerably; sometimes it is elevated 

 posteriorly and slopes steeply down anteriorly, sometimes it has an evenly rounded 

 crest and is nearly as much elevated anteriorly as posteriorly. The transverse 

 processes are well marked. 



dr- 



Fig. 2. — A Atlas, front view ; g Atlas, seen from above : C Axis, left side view. All \ natural size. All from 

 Barring-ton and preserved in the Sedgwick Museum, Cambridge, a, neural spine ; b, neural canal ; c, surface 

 for articulation with condyles of skull ; d, odontoid process (broken) ; «, transverse process : /, surface for 

 articulation with atlas ; g, postzygapophysis. 



The remaining cervicah (Text-fig. 3) have the anterior surface of the centrum, 

 which retains all through the series a very uniform length, very slightly convex, 

 and the corresponding posterior surface very slightly concave. The transverse 

 processes are prominent and have descending flanges, which increase somewhat in 

 size in the later vertebrae. The seventh is, however, without a descending flange. 

 The neural spines, except that of the seventh, are of no great size and increase 

 3 



