464 University of California Publications in Zoology — [Vow. 17 
sometimes nearer light pinkish cinnamon, sometimes nearer pinkish 
buff; general undertone of coloration ventrally pale drab-gray, with 
an insprinkling of varying numbers of blackish, whitish, cinnamon or 
buffy hairs; irregular areas of hair white from base to tip appearing 
in most of the males ventrally. 
Sexual Differences.—The conspicuous white patches ventrally ap- 
pear in males only, all the examples of that sex showing them to a 
greater or less extent. The spot marks about the mammae in May and 
July females are less conspicuous than usual. Of two females taken 
in July, one (no. 1894, Mus. Comp. Zool.) has the hair about the 
mammae practically worn off, while the other (no. 1895, Mus. Comp. 
Zool.) has the hair in the same region unworn. It seems likely that 
the condition of the hair about the mammae may be taken as an index 
to breeding activity. 
CRANIAL MEASUREMENTS OF Aplodontia rufa columbiana (9 SKULLS) 
Average Mean Maximum Minimum 
Wen oth sorte nasallse (/ees ks) pcos eee eee 29.3 29.5 30.9 28.2 
Width of nasals 12.8 12.9 13.8 12.0 
Length of incisive foramen 8.0 7.8 8.5 1.2 
Zygomatic width 62.3 60.9 64.0 57.9 
Mastoid width ‘of eramiumy 2cete ete ceereee cree 57.5 57.2 61.2 53.2 
Alveolar length superior cheek teeth . 19.3 19.3 19.8 18.8 
Distance between infraorbital foramina 16.9 17.2 18.3 16.2 
Mandible, transversely across angular process .... 24.6 24.5 26.1 23.0 
Mandible ereatest Lemp tl) 22sec cre eee 51.2 51.9 54.9 48.9 
EXTERNAL MEASUREMENTS OF Aplodontia rufa columbiana (9 SKINS) 
Average Mean Maximum Minimum 
Mortal len orthig ecco 427 425 470 380 
Remarks.—Available material indicates intergradation between 
Aplodontia rufa columbiana and A. r. rufa on the one hand and A. r. 
rainiert on the other. Specimens in the United States National Museum 
. : 30739 3089 
from the head of the Cascade River, Washington (nos. 22732 30890 
426399 
42790’ 
Biol. Sury. Coll.) are intermediate between columbiana and rainieri, 
although perhaps a trifle closer to the former. If, as seems likely, the 
distribution of Aplodontia is more or less continuous between Mount 
Rainier and the mountains in the Hope District, British Columbia, it 
is probable that one grades into the other by insensible degrees. Aside 
from its greater dimensions columbiana may be separated from rufa 
through its smaller-calibered, more pinched-up audital tubes, as com- 
pared with the larger, rounder tubes of rufa. Columbiana also has the 
zygomatie arch more expanded posteriorly than in rufa, as well as 
broader nasals posteriorly, and more closely approximated temporal 
