1^-4] Grinnell-D ixon : The Genus Lynx in California 343 



is relatively broad, smooth, and rounded, while the sagittal crest is 

 scarcely discernible. On the other hand, the skull of a very old male 

 (no. 29786) as compared with the usual run of youngish specimens 

 (such, for instance, as the type of oculeus), presents a long narrow 

 appearance. The rostrum is long and strong; the post-orbital pro- 

 cesses are prominent, their tips nearly meeting the opposite processes 

 from the malars to form a nearly complete orbital boundary; imme- 

 diately behind the post-orbital processes there is a marked constriction 

 of the brain case ; the brain case does not strike the observer as full and 

 rounded but is thrown into the shade, as it were, by the very promi- 

 nent, backward projecting sagittal crest, the outward extending mas- 

 toid processes, and the interconnecting lambdoid ridges. The median 

 shf^rp sagittal ridge in this specimen is 25 millimeters long, and the two 

 temporal muscle impressions forward of this crest, at the fronto- 

 parietal sutures, approach within 12.5 mm. of one another. Curiously, 

 wildcats' teeth do not seem to be subject to much wear or breakage 

 as are the teeth of bears and coyotes; so that comparative age can 

 be determined better by degree of development of the attachments for 

 muscles and by the stage reached in the effacement of sutures than by 

 degree of wear shown by the teeth. 



It is worthy of remark in this connection that really old wildcats 

 have come in to the Museum only in very small proportion to the total 

 number. Out of the series from the Yosemite region, we consider 

 nine to be immature, six to be young-adult, eleven to be fairly adult 

 or mature, and just three to be really old. The actual ages represented 

 by these classes, in months or years, we have no present means of 

 knowing. Obviously, the chances are that a small collection, with a 

 very few specimens from any one locality, is unlikely to contain any 

 good old adults. Even the Yosemite series is unfair as to true pro- 

 portions of old and young, for we had in some cases posted the 

 trapper (for fur) to save especially the "big" skulls for us. 



Then, with respect to sex, the skulls of males are on the average 

 larger, longer, and more sharply ridged than those of females of the 

 same age. The difference here is nowhere near what it is in the moun- 

 tain lion ; still it is so noteworthy that sex must always be taken into 

 consideration. The weights of two fairly adult, air-dry skulls without 

 lower jaws, shown by all the indications to be of nearly the same age, 

 no. 23881 male, and no. 23880 female, both from Hetch Hetchy Valley, 

 Tuolumne County, are, respectively, 55.3 and 43.2 grams. In other 

 words, on this basis, which probably involves relative mass of bone 

 and tooth material in the skull, females are but 78 per cent of the 



