NO. 2196. EFFECTS OF ENVIRONMENT ON LIONS— HOLLISTER. 191 



lation on its meaning or the possible value of the records in the study 

 of evolution is contemplated. The opportunity for such speculation, 

 however, is unlimited, and the temptation is great. This remark- 

 able change has taken place in the lions under artificial treatment. 

 Might some such a change not happen in a state of nature? At 

 numerous times in geologic history whole groups of animals have 

 become extinct. In fact, this is the rule, and only a few of the types 

 known from fossil remains have left living descendants. If all the 

 imgulate mammals of Africa or in some one extensive region were 

 swept away in a few years by a plague like the rinderpest, would 

 the lion die out, or would he completely change his habits in one 

 generation and become a feeder on mice, squirrels, birds, and fruit? 

 In the latter case, would not the enforced disuse of the powerful 

 mechanism for the destruction of zebras, hartebeest, and larger game 

 produce in one generation, as with the park lions, a type of skull 

 wholly different from that now known in a state of nature? 



One can easily believe that if the ordinary wild lion skulls were 

 known only from Miocene deposits and the specimens were com- 

 pared with the MciVIillan lion skulls, they might be regarded as rep- 

 resenting the ancestor of the latter. The great change would natu- 

 rally be regarded as the result of slow variation continued over that 

 long period of time. 



The use of zoological park material in the description of new forms 

 of mammals should be discouraged. New names should never be 

 based on animals in parks or on skins and skulls of specimens which 

 have lived long in captivity. 



Relative dimensions (ratio of length to breadth) of skulls is shown 

 by the McMillan lions to be easily changed by habit or environment. 

 Great weight has often been placed on the ratio of length to breadth, 

 as a deep-seated character. Paleontologists, especially, value such 

 differences much higher than do workers in recent mammals who 

 have access to large series of closely related subspecies and are fa- 

 miliar with the variations they exhibit in this respect. The surpris- 

 ing and uniform differences in this regard between the McMillan 

 lion skulls and the skulls of wild-reared examples of Felis leo mas- 

 saica are, nevertheless, a revelation to all mammalogists who have 

 seen the specimens. 



left temporal muscle of a puppy at birth and the subsequent dissection of the animal 

 at or near maturity, have shown the importance of the study of the action and growth 

 of the muscles, exercised by peculiar habit, in the formation of species. (See especially 

 Anthony, Bull. Sci. Anthr. Paris, ser. 5, vol. 4, 1903, pp. 119-145, figs. 1-11. Anthony 

 and I'ietkiewicz, C. R. Acad. Sci., vol. 149, 1909, p. 870, and other papers by the same 

 authors.) 



