98 PROFESSOR OWEN ON THE OSTEOLOGY OF 
proportion to its breadth than in the Gorilla, Chimpanzee, or Orang. The surface for the 
odontoid process, or true body of the atlas, is more nearly circular and better defined. The 
vertebral artery, after perforating the transverse process, grooves the neural arch behind 
the produced angles of the upper zygapophysis (fig. 8, z). The cavity for the occipital 
condyle is relatively larger, deeper, with the margins more produced. The parapophysial 
boundary (p) of the vertebral arterial foramen (v) is thicker than the diapophysial 
one (d) ; they are equal in the Gorilla: the arterial foramina are relatively larger and 
the lower zygapophyses (fig. 9, z') are relatively much larger than in the Gorilla. 
These differences chiefly relate to the more secure articulation and support of the 
vertically-sustained head, and to the larger size of the cerebral organ, in part nourished 
by the vertebral arteries, in the Human species. The development of the zygapophyses 
gives a greater antero-posterior extent to those parts of the atlas, and the transverse 
processes are thicker in proportion to their length. 
In the Australian the anterior surface of the body of the dentata (fig. 10) is less 
flattened than in the Gorilla (fig. 4) or Chimpanzee, the middle line being produced 
almost into a ridge; its hinder border is more rounded. ‘Che transverse process (pl) is 
thicker and more obtuse in proportion to its length: both the anterior and posterior 
zygapophyses are relatively larger: the neural canal is relatively wider transversely : 
the neural spine is much less developed : in fact, what is usually described as the bifur- 
cated spine of the axis seems rather to be the upper slightly-produced extremities of the 
not completely coalesced neurapophyses of that vertebra in Man. Lines drawn parallel 
with the transverse plane of the anterior zygapophyses would meet at a right angle in 
the Chimpanzee, but at a more open angle in Man, especially in the White races. 
In the third cervical vertebra (fig. 7,3), the upper angle of the base of each neur- 
apophysis is produced forwards beyond the centrum, and assists in forming, but in a less 
proportion than in the Gorilla or Chimpanzee, the transverse concavity for the produced 
body of the axis. The centrum is larger in proportion to the rest of the vertebra than 
in the Chimpanzee, save in its length. The pleurapophysial part (pl) of the transverse 
process forms a distinct obtuse angle from the diapophysial part, which is shorter, thicker 
and more obtuse than in the Chimpanzee. The same difference is here repeated in the 
greater relative size of the zygapophyses, particularly the anterior ones. The transverse 
diameter of the neural canal is relatively greater. The neural spine (xs) is very much 
shorter than in the Goriila : it is, however, simple, not bifurcate, as usually in Europeans. 
In the fourth cervical vertebra (id. 4) the sides of the upper concavity of the body are 
still formed by the neurapophyses, which are less produced than in the preceding ver- 
tebre, or than in the corresponding vertebre of the Gorilla. ‘The diapophyses are 
shorter than in the Chimpanzee ; the neural spine is considerably shorter than in the 
Gorilla. The zygapophyses are relatively larger. The pleurapophysial and diapophysial 
parts of the transverse process are nearly equally developed, and are bent upwards on 
the sides of the groove which impresses the upper part of the transverse process. The 
