1911] Taylor: Mammals of the 1909 Nevada Expedition. 245 



These figures prove that the statement above quoted does not 

 hold in the four aged adult specimens. 



The tongues of the premaxillaries extending back of the 

 nasals are relatively broader than in desertorum, as stated in the 

 description of nevadensis. 



The hamular processes in the four skulls are very nearly as in 

 desertoricm. 



Two of them (nos. 78284, 78283) show a bay in the dorsal 

 contour of the foramen magnum, the others resembling deser- 

 torum in this respect. 



A tendency seems to exist in the skulls at hand for the pre- 

 sphenoid bar separating the sphenopalatine vacuities to be 

 actually narrower in old age. Even taking this fact into account, 

 and remembering that the four skulls here considered are 

 extremely old specimens, in them the bar seems to be somewhat 

 broader (especially in no. 78287) than in desertorum, though 

 the difference is slight. 



The mandibles are not less massive in the Deep Hole and 

 Granite Creek series than in desertorum. One of the Deep Hole 

 examples (no. 78284) has the bay in the mandible like deser- 

 torum. Two others (nos. 78283, 78289) have the condition as 

 described for nevadensis. The mandible of the other specimen 

 (no. 78287) is broken. 



Considerable variation exists in the skulls in respect to 

 anterior roots of zygomata. On the whole they seem to be broader 

 than in desertorum. The posterior roots, however, seem to be 

 slightly narrower, even in the larger skulls, which fact harmon- 

 izes with the description of -nevadensis. 



The interparietal in the four skulls is similar to that of deser- 

 torum. 



The auditory bullae are more swollen, as adduced for neva- 

 densis, as is shown by the measurement "height of cranium at 

 auditory bullae." 



In the light of these considerations, the most important 

 cranial characters are, first, the greater ratio of the height of 

 cranium at bullae to length of skull, probably due to bullae being 

 slightly more swollen ; second, po.steriorly extending tongues of 

 premaxillaries broader; third, posterior roots of zygomatic arches 

 narrower. 



