342 University of Califoniia Puhlications in Zoology [Vol. 21 



The wildcat's pelage, of a very soft silky texture, seems to be far 

 less durable than that of most fur-bearers. Exposure to daylight, even 

 if not direct sunlight, and also to dryness, as another probable factor, 

 affects the substance of the hairs in such a way that they become 

 brittle, and at the same time the pigment in them is modified. Wear 

 and fading are processes that seemingly go together, and the rapidity 

 with which they proceed varies directly with the intensity or duration 

 of the exposure. While wildcats are active abroad chiefly during dark- 

 ness or at least the twilight hours, they are known sometimes to bask 

 in sunshine of moderate intensity, and sunshine in a dry climate of 

 clear atmosphere acts very rapidly. 



In addition to the wide seasonal variation in coloration, there is 

 marked individual variation. This involves tones of color and extent 

 of markings. Some individuals, in exactly the same condition of 

 pelage, are markedly browner, less gray, than others. There may be 

 a more, and a less, distinct or coarser pattern of spotting on the sides 

 and legs. The barring of the tail, which has been cited as a good 

 specific character, is far from uniform. In this regard, Stephens 

 (1906, pp. 210-211) makes some important comments. He says: 

 "Before me lie seventeen Lynx skins taken in one locality (35 miles 

 nortfieast of San Diego), all prepared and measured by myself, there- 

 fore strictly comparable. . . . They vary greatly in amount of spot- 

 ting, shade of color, size of ear tuft and barring of tail, dependent on 

 age, season and wear of pelage. . . . The tails of two have black tips 

 with no bars, while others have two to six bars. ' ' 



All this variation must be taken judiciously into account when 

 seeking external characters, or a mean of them, which can properly 

 be used for characterizing true species or subspecies. 



Cranial variations. — Our best series of skulls from any single small 

 area, such as is suitable for the basis of studying individual variation, 

 consists of 29 examples from the west slope of the central Sierra 

 Nevada, in Tuolumne and Mariposa counties. Most of these were 

 obtained within the Yosemite National Park. The variations shown 

 among these are of more or less wide extent in accordance with (1) 

 age, (2) sex, and (3) the individual. 



Naturally the greatest variation is with age and involves propor- 

 tions as well as general size. In half -grown individuals, for example, 

 no. 21575 (in which the permanent teeth are just coming in), the 

 rostrum is, as compared with older individuals, relatively short, the 

 post-orbital processes are small, the interorbital width is small but the 

 breadth at the post-orbital "constriction" is very great, the brain ease 



