160 BULLETIN 99, UNITED STATES NATIONAL MUSEUM. 



natural tendency of carnivores to bolt their food without chewing, 

 the temporal muscles are used by them in an essentially normal way. 

 These muscles, unlike the disused masseters, have moulded the parts 

 of the growing skull to which they are attached in more nearly the 

 same manner as in wild individuals. The region of origin, the entu-e 

 side of the skull posteriorly, is somewhat modified. The braincase 

 has been less subjected to pressure by these powerful muscles than in 

 the wild Hon, and it, as a consequence, is less compressed laterally. 

 Wild lion skulls of equal age have smaller braincases, and more sharply 

 marked sagittal and lambdoidal crests. The region of insertion, the 

 inner surface of the ascending ramus, is slightly smoother in the 

 McMillan skulls, but is little modified. 



TJie mastoid and occipital regions. — These regions are, except for 

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

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

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

 Hons 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 [m wild hons the mastoid breadth is usually 

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

 external surfaces of the mastoids he in a position at a much greater 

 angle from the general occipital plane; marginal ridges sharply 

 recm-ved; paroccipital process longer and more angular]. (See 

 pi. 55.) 



Nondevelopment of the muscles chiefly used in liftmg and shakiug 

 prey and the consequent lack of necessity for strong attaclnnents is 

 clearly responsible for this pecuharity 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 hon, 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 

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

 muscles, naturally less developed in the animal reared in captivity. 

 The digastric muscle, of quite another function, but powerfully 

 developed in the cat, and having its origin on the paroccipital 

 process and inward, bordering the posterior margin of the auditory 

 buUse, is no doubt somewhat responsible for the development of shape 

 in this part of the skull as well. After a preliminary movement of 

 the hyoid muscles, it is the chief agent for depressing the jaw. The 

 cephalo-humeral and other muscles and the iigamentum nuchse 

 attach to the base of the skull, but in this problem are of httle im- 

 portance. 



