190 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 53. 



Dental measurements of adult Felis leo massaica — Continued. 



Locality. 



Number. 



Alveolar 



length cf 



upper 



Upper 

 camassial. 



Second upper 

 premolar. 



Lower molar. 



Wild-killed females. 



Dlu Station 



Do 



Do 



Kapiti Station 



Do 



Do 



Do , 



Do 



WamiHill 



Kitanga 



McMillan females. 



182308 

 182309 

 182311 

 182293 

 182324 

 182326 

 182421 

 182423 

 161914 

 182315 



197137 

 199524 



mm,. 

 23.6 

 24.9 

 20.7 

 21.9 

 20.9 

 19.4 

 21.9 

 21.2 

 21.7 

 23.2 



19.1 

 19.2 



mm. 

 35.4X17.7 

 38.5X19.4 

 33.6 X 15.9 

 35.2X17.1 

 33.9X16.8 

 33.2X15.5 

 32.5 X 16.3 

 33.1X17.0 

 33.4X15.6 

 35.6X16.5 



33.6X15.2 

 32.5X15.4 



mm. 

 23.8X11.7 

 27.7X14.1 

 22.3X11.5 

 23.7X12.9 

 23.6X11.7 

 22.1X11.2 

 23.1X12.2 

 21.8X12.5 

 i 21.7X11.1 

 22.2 X 12.0 



22.9X10.5 

 21.7X11.3 



mm. 

 25.1X12.7 

 28.4X14.6 

 24.6X13.2 

 25.3X13.9 

 25.3X12.4 

 23.9X12.1 

 23.3X12.7 

 24.6X13.6 

 24.2X12.1 

 25.6X13.2 



23.8X11.9 

 22.9 X 12.4 



SUMMARY. 



Specimens of the exceedingly pale Felis leo massaica brought from 

 the British East African highlands to Washington change from the 

 normal pale grayish buff color of the race to a darker color, re- 

 sembling that of Felis leo nyanzce of the Victoria Nyanza re- 

 gion. The color deepens with each successive moult for five years 

 at least. The cause of this color change is unknown, though humidity 

 is probably a factor of some importance. 



The skulls of lions and other large carnivores which habitually 

 kill quantities of heavy game are greatly influenced in a definite 

 way by the development of the principal muscles used in gripping, 

 holding, tearing, biting, and shaking. If the animals are captured 

 when young and reared in confinement these particular muscles are 

 little developed and the bone at the region of origin or insertion is 

 little changed by their influence. The bones then retain certain 

 characteristics of juvenility and develop along wholly different but 

 uniform lines from that of the wild-reared animal. 



Changes in the skull which would be accepted as of " specific " or 

 possibly of " generic " value in wild animals from different regions 

 are thus produced in the life of a single individual within from five 

 to seven or eight years, almost as rapidly as if by " mutation." 



The primary object of this paper is to call attention to a definite 

 case of structural modification by habit.^ No idea of extensive specu- 



1 The value of evidence derived from this case over that furnished by experimental 

 mutilation of young animals can easily be appreciated. Nevertheless experiments such 

 as those recorded by Anthony and others, like the removal of the greater part of the 



