466 University of California Publications in Zoology — [Vou. 17 
The youngest specimens all have this measurement broad. In some 
of the older ones it is broad, in others narrow. The zygomata are 
usually squarer and more expanded in the adults than in the young. 
The mastoid process is exceeded by the audital tube in all the adults, 
being, however, only slightly exceeded in the oldest ones, while in 
young specimens the audital tube materially exceeds the mastoid 
process. The width of the palate between the third premolar and the 
incisive foramina remains about the same, or even increases slightly, 
with age. Looking at the crania in side view, the ventral outline of 
the rostrum is nearly plane in the young, with slight eminences ob- 
servable at the posterior end of the incisive foramina. In the adults 
the outline tends to be more rounded, the slight eminences having 
disappeared. 
Molt.—Specimens collected on Mount Rainier on August 6 and 7 
are with one exception (no. 90143, 9, U.S. Nat. Mus., Biol. Surv. Coll.) 
beginning to molt. In one example (no. 90145, 9, U. S. Nat. Mus., 
Biol. Surv. Coll.) hair renewal is taking place on small areas on the 
sides; in another (no. 90144, 4) new hair is coming in on the right 
side only on an area one inch wide and four inches long, as well as 
in an irregular area on the top of the head; still another (no. 90137, ¢) 
is molting extensively laterally as well as in a small area on the head. 
The condition of this specimen suggests that the molt begins on the 
sides, and sometimes becomes quite extensive before the head molt 
starts at all. 
CRANIAL MEASUREMENTS OF TYPE AND TOPOTYPES OF Aplodontia rufa rainieri 
(4 SKULLS) 
Average Mean Maximum Minimum 
Basilar length 62.1 63.6 65.4 61.9 
Length of nasals (3 skulls) 
Width of nasals 12.7 14.0 11.4 
Length of audital tube (2 skulls) 19.1 19°9 18.4 
Length of incisive foramen .-........... tlstf 8.2 7.2 
iy PROAEKOSAMG UTE | sone toe en smack anes one eace aos : 58.6 62.0 55.3 
Greatest width of interpterygoid fossa 5.6 5.9 5.4 
Mastoid width of cranium 55.6 57.8 53.5 
Alveolar length superior cheek teeth —. 19.9 21.0 18.9 
Distance between infraorbital foramina : . Ufeil 18.1 16.2 
Mandible, transversely across angular process ... 25.7 26.0 28.2 23.9 
Mandible, greatest length —...--.------2.---.2---te-=---- 50.8 50.8 52.9 48.8 
EXTERNAL MEASUREMENTS OF TyPE AND ToporTyPES oF Aplodontia rufa rainieri 
(4 Skins) 
Average Mean Maximum Minimum 
Total length 377 379 384 365 
TBnC GGL AKO YO poets cee ce 62 63 65 62 
