380 University of California Publications in Zoology [Vol. 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. prinoeps, a supposition which is borne 

 out in a measure by its distribution in northern British Columbia. There it 

 supplements in some degree the Eocky Mountain distribution of Z. princeps, 

 reaching the coast from the mouth of the Skeena northward. The Z. litidsonius 

 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. Tour Eevillagigedo Island (Portage Bay) specimen may 

 represent an intrusion from the noi-th, where Z. liudsonius (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 IniAsonius. 



Erethizon epixanthum nigrescens Allen. Dusky Porcupine 



Porcupines 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 slides, 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 Erethizon epixanthum nigrescens AUen. Number 32755. yellowish 

 in general appearance, is not to be distinguished in color from four 

 California specimens at hand. 



Porcupine skulls are said to exhibit great individual variation (see 

 Hollister, 1912&, p. 27), but as far as our series goes, there are cranial 

 characters which can be used to differentiate the animals of British 



