380 University of California Publications in Zoology  |Vou. 24

about eighty miles north of the mouth of the Skeena River. Much
collecting must be done, and in localities as yet unworked, before an
understanding can be reached regarding the distribution and relation-
ships of the species of Zapus occurring in the northwest, but certain
ideas of Mr. Preble, expressed to me in a letter, seem to point so
surely toward a solution of the problem, in its general features, that
I append his comments here.

I believe Z. saltator to be related to Z. princeps, a supposition which is borne
out in a measure by its distribution in northern British Columbia. There it
supplements in some degree the Rocky Mountain distribution of Z. princeps,
reaching the coast from the mouth of the Skeena northward. The Z. hudsonius
group has evidently intruded into British Columbia from the east, being repre-
sented by the colony named Z. tenellus, and by your Hazelton specimens, Doubtless
it covers a wide area. Your Revillagigedo Island (Portage Bay) specimen may
represent an intrusion from the north, where Z. hudsonius (or alascensis) is
common. Zapus h. alascensis, though recognizable in its typical form, is a rather
faintly characterized subspecies, and the Portage Bay specimen, like the
Hazelton ones, is very close to typical hudsonius.

Erethizon epixanthum nigrescens Allen. Dusky Porcupine

Poreupines were abundant at timber line on Nine-mile Mountain.
The lowlands are doubtless visited frequently during the winter
months, but in summer the species seems to be rather closely restricted
to the Hudsonian Zone of the higher mountains. Rock sldes, just
‘above the limit of upright timber, evidently form the preferred
habitat. The animals were numerous enough to be a decided nuisance.
They are nocturnal for the most part, and but few were seen abroad
in daylight; activities began at dusk, and during the three weeks we
spent upon the mountain there was not one night when we were not
disturbed by visiting porcupines.

Three specimens were preserved: no. 32755, skin and skull; no.
32757, skin and skull; no. 32756, complete skeleton. All are adult
males. There was great variation in color among the animals we saw;
the two skins preserved were taken as representing extremes of light
and dark coloration. Number 32757 is very dark, black in general
effect, and is doubtless the same sort of animal as served as the type
of Hrethizon epixanthum nigrescens Allen. Number 32755. yellowish
in general appearance, is not to be distinguished in color from four
California specimens at hand.

Poreupine skulls are said to exhibit great individual variation (see
Hollister, 19120, p. 27), but as far as our series goes, there are cranial
characters which can be used to differentiate the animals of British