184 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 63. 



Mr. Selous has noted that while the eyes of wild lions are of a 

 " flaming yellow " in color, those of animals reared in captivity are 

 often brownish. 



Skull Chabactebistics. 



The greatest interest in the study of the McMillan lions compared 

 with wild examples from the same region lies in the skull. The 

 skulls of the captive animals are of a definite, uniform shape and 

 differ from all the skulls of wild-killed lions in the Museum col- 

 lection in a number of conspicuous characters. They are broader 

 and shorter, more massive and bulky, and exhibit abundant relative 

 differences which would be instantly accepted as of " specific " value 

 in wild animals. The obvious reason ;for these great differences is 

 that the principal muscles operating the jaws and neck (those 

 muscles used by a wild lion in mauling and killing game, biting, 

 gripping, and shaking) have had little influence on the shape of the 

 bones during development. In a wild-reared lion these powerful 

 muscles naturally and in a normal way mold the growing skull, par- 

 ticularly in the regions of their attachment. 



The most conspicuous peculiarities of the McMillan lion slcuUs 

 are the greater (relative and actual) zygomatic breadth, the large 

 rostra, and the great distance across the base of the skull at the mas- 

 toids. While actually measuring less in condvlobasal or greatest 

 length than many of the wild massaica skulls of equal age, they 

 have a far greater zygomatic breadth than any, averaging about 30 

 millimeters more in males and 20 millimeters more in females. (See 

 detailed measurements, p. 192; and pi. 24.) 



All five of the McMillan lions, male and female, are, as already noted, 

 fully adult, the skulls with basal sutures obliterated. All agree in 

 most particulars in the differentiating characteristics, and compari- 

 sons may be made with wild-killed skulls of Felis leo massaica from 

 the same vicinity and of equal age, without special designation of 

 specimens by number. The differences are sometimes most pro- 

 nounced in males. 



Regions of attachment of the massete?' muscle. — Contrary to the 

 usual textbook definition of its function, the masseter muscle un- 

 questionably furnishes the chief gripping power; it is the one most 

 exercised during use of the canine and incisor teeth.'^ Aided by the 



' In this connection see Keith, The Antiquity of Man, 1915, pp. 4C2-4G3. The lion, 

 like all cats, is a biting animal of the highest type. While there is intimate relationship 

 between the functions of the masseter and temporal muscles, and the two masses are 

 actually connected, each nevertheless is the prime power in the definite mechanical action 

 of separate parts of the dental row. The masseter, as stated above, has primarily to 

 do with the front teeth (the canines and incisors), while the temporal is chiefly con- 

 cerned with the niolar-premolar row, and the process of cutting and chewing rather 

 than biting and gripping. 



