NO. 2190. EFFECTS OF ENVIRONMENT ON LIONS— HOLLISTEB. 



187 



Following are some measurements of the capacity of the brain- 

 case in fully adult lions: 



MALES. 



FEMALES. 



» McMillan lions. These are the only park-reared skulls strictly comparable with wild-killed F. I. 

 massaica. 



The mastoid and occipital regions. — ^These regions are, except for 

 the squamosal arm of the zygoma, the most modified parts of the 

 park-reared lion skulls. The change from the uniform type found 

 in the wild lion is very great. The mastoid breadth in the McMillan 

 lions is far greater than is usual in wild skulls of equal age; the 

 mastoids are broad and spreading, with the large, smooth, postero- 

 external surfaces next to the paroccipital process only slightly turned 

 forward from the general occipital plane, and without sharply 

 marked marginal ridges [in wild lions the mastoid breadth is 

 usually much less, the sides are drawn in and forward, so that the 

 postero-external surfaces of the mastoids lie in a position at a much 

 greater angle from the general occipital plane; marginal ridges 

 sharply recurved; paroccipital process longer and more angular]. 

 (See pi. 25.) 



Nondevelopment of the muscles chiefly used in lifting and shaking 

 prey and the consequent lack of necessity for strong attachments is 

 clearly responsible for this difference in the park- reared animals. 

 The splenius, complexus, rhomboideus capitis, cleido-mastoid, sterno 

 mastoid, rectus capitis posticus major, and rectus capitis posticus 

 minor all attach to the affected parts. A powerful splenius is neces- 

 sary in the wild lion, as the beast commonly carries heavy prey for 

 long distances; the well-developed rhomboideus capitis aids in this 

 work. The complexus and mastoid muscles are of great power in the 

 shaking process and are, like the splenius and other closely related 



