MAMMALIA. 



659 



Fig. 309. 



sist the strong pressure of the enormous temporal muscles. 

 This is given by adding strong buttresses to the outer angle of 

 the orbit formed by the union 

 of the frontal and the jugal 

 bones, and thus the whole out- 

 line of the face becomes more 

 humanized. 



Another advance towards the 

 condition of the human skull is 

 apparent in the position of the 

 foramen magnum, and of the 

 condyles of the occipital bone, 

 which are now considerably ad- 

 vanced forwards beneath the 

 base of the cranium, thus allow- 

 ing the head to be articulated to 

 the atlas at a very considerable 

 angle with a line drawn through 

 the axis of the spine ; a condi- 

 tion evidently favourable to the 

 erect posture. 



The thorax is well formed 

 and capacious, giving great free- 

 dom of respiration ; but the spi- 1 

 nal column is short and clumsy, 

 neither does it present those 

 graceful sigmoid curves that con- 

 vert the human spine into a per- 

 fect spring, upon the top of 

 which the head is carried. 



The arms are of inordinate 

 length and extremely powerful ; 



the joints perfect, and the clavicle well formed. But in the con- 

 struction of the pelvic extremities the differences between this and 

 the human skeleton become strikingly apparent. The pelvis is 

 long, and the ossa ilii narrow ; the thighs and legs so short, that, 

 when the creature stands erect, the tips of the fingers almost touch 

 the ground. The protuberance of the os calcis is very slight ; and 

 thus the posterior hands, although well adapted for taking hold of 

 any object, are but ill calculated to sustain the weight of the body 

 in an upright posture. Upon the ground, indeed, the living 



