176 University of California Publications in Zoology V^ou 24 



much-traveled runways. The shelter afforded by' rail fences and the 

 sides of the crumbling houses was also taken advantage of, and traps 

 placed in such situations yielded mice night after night. A great 

 many more were caught at that station than -the thirty-eight that were 

 preserved. 



At Doch-da-on Creek, this meadow mouse was not especially abun- 

 dant. Most that were caught were taken in weed-grown bottom lands. 

 At Flood Glacier, well defined runways, with many little piles of 

 freshly cut green stuff, gave an appearance of an abundance of 

 meadow mice, but despite the plentiful sign, specimens were taken but 

 slowly. Apparently one full-grown Microtus can establish and operate 

 an elaborate system of runways. One weed-grown area some fifty feet 

 square, intersected with well used paths in which were found fifteen 

 or twenty little piles of freshly cut green weed stems, yielded just one 

 adult meadow mouse. At Great Glacier but two specimens were 

 trapped. 



The occurrence of a meadow mouse of the longicaudus group over 

 the entire length of the Stikine River is of interest as bearing upon 

 the relationship of Microtus mordax of the interior and M. macrurus 

 of the coast. The two forms are closely related, and though hereto- 

 fore recognized as distinct species, the differences between them are 

 comparable to what is found among subspecies of some one species in 

 other sections of the genus. The main differences between the two 

 are of coloration and of length of tail. There are skull differences 

 also but not trenchant ones. Macrurus, like other coastal species, is 

 of dark brownish coloration, quite reddish-brown dorsally; mordax 

 is distinctly gray. Macrurus hgs a longer tail than mo7-dax, longer in 

 actual measurement and longer in relation to total length. Both 

 macrurus and mordax in the northern parts of their respective ranges 

 (southeastern Alaska and northern British Columbia) are somewhat 

 smaller than they are at their southern limits. 



We obtained long-tailed meadow mice at various points on the 

 Stikine River down as far as Great Glacier, and I have at hand several 

 additional specimens (from the collection of E. P. Walker) taken at 

 Clearwater Creek, just below the British Columbia-Alaska boundary 

 line. There are also available specimens from Wrangell and Mitkof 

 islands (near the mouth of the Stikine), and from various points on 

 the mainland short distances north and south of the mouth of the 

 river. Macrurus is abundantly represented in the collection of this 

 Museum from various points in the Alexander Archipelago. 



