CHAPTER X. 



THE SKULL IN THE ORDER PRIMATES, CARNIVORA, 

 INSECTIVORA, CKIROPTERA, AND RODENTIA. 



Order Primates. Man. — On comparing a longitudinal 

 and vertical section of a young human skull, in which most 

 of the sutures are still distinctly seen (Fig. 49), with that of 

 the Dog, it will be seen to be composed of the same bones, 

 having very nearly the same connections, and yet the whole 

 form is greatly modified. This modification is mainly due 

 to the immense expansion of the upper part of the middle 

 or cerebral fossa of the brain cavity, which not only carries 

 the roof of the cavity a great distance from the basicranial 

 axis, but also forces, as it were, the anterior and posterior 

 walls from the vertical nearly to the horizontal position, so 

 that they are, roughly speaking, in the same line with the 

 short basicranial axis, instead of being perpendicular to it. 

 In addition to this great difference, the facial portion of the 

 skull is deeper from above downwards, and very much 

 shorter from before backwards. 



Taking a survey of the human skull in the same order 

 as was done with that of the Dog, we find the craniofacial 

 axis, composed of the basioccipital bone {BO), terminating 

 at the anterior border of the foramen magnum (/;«) behind, 

 and in this young skull still separated from the basisphenoid 



