AMERICAN BATS OF THE GENERA MYOTIS AND PIZONYX 141 



This is the dark form of the humid coast region of the Northwest. 

 The most northerly locality known for it is Mole Harbor, Admiralty 

 Island, in southwestern Alaska, whence the University of California 

 has a specimen taken June 9, 1907. Thence southward it occurs in 

 British Columbia as well as in western Alberta, where at Henry 

 House, the type specimen of Myotis altifrons was captured. This 

 last, however, proves to be inseparable from M. v. longicrus. South- 

 ward again, typically dark examples are found from the Cascade 

 Range to the coast in the western half of Washington and Oregon, 

 while in California it is present coastwise in Humboldt, Mendocino, 

 Sonoma, and Marin Counties as far south at least as San Mateo and 

 Monterey Counties. Inland from this area there is a lessening of 

 the saturate appearance, and adult specimens show a distinctly lighter 

 or ochraceous-tawny cast. This is true of skins from eastern Oregon, 

 and the Sierra Nevada of California from Mount Shasta southward 

 to Mount Whitney. These are more or less intermediate between M. 

 V. longicrus and M. v. interior^ and occasional specimens from the 

 central portions of the Sierra may be referred with almost equal 

 propriety to either form, as has been shown by Mrs. Grinnell (1918, 

 for Mono County). On the whole, however, the Sierra Nevada 

 series seem best placed with the brighter race, interior. Immature 

 individuals are, of course, much darker than adults and lack almost 

 entirely the ruddy golden tint of adults of M. v. inferior, so that their 

 general appearance is nearly as in worn adults of M. v. longicrus. 



Diagnosis. — Darkest of the subspecies, general color dark reddish 

 brown above, smoky below ; size greater than in typical Myotis volans 

 (forearm 37 to 40; tibia 18 to 19.6; greatest length of skull 13.7 to 

 14.6 mm.). 



Color. — In fresh unworn pelage the tips of the longer hairs are a 

 very dark reddish brown above — near cinnamon brown of Ridg- 

 waj — recalling the color of Myotis lucifugus Imcifugus; below, smoky 

 brown, paler posteriorly; the bases of the hairs blackish; ears and 

 membranes blackish. 



Most of the skins available were collected in late summer and seem 

 to have lost much of the long reddish tips of the hairs through wear, 

 and in general are a dark smoky brown ( a little darker than Prout's 

 brown), paler below. 



A specimen from Admiralty Island, Alaska, is blackish brown with 

 very little of the cinnamon tipping on the back, but is closely matched 

 by some of the skins from Washington. 



Measuretnents. — For measurements, see tables, pages 146 and 147. 



Specimens exa/mined. — Total number 127, from the following 

 localities : 



ALASKA: Admiralty Island, Mole Harbor, 1 skin (U.C). 

 ALBERTA: Henry House, 1 skin, type of altifrons (U.S.N.M.). 



