AMERICAN BATS OF THE GENERA MYOTIS AND PIZONYX 51 



Type locality, — Yellowstone Park, Wyo. 



Type specimen. — Adult female, in alcohol. No. 4.4.25.1, British 

 Museum (Natural History), collected at Yellowstone Lake, Yellow- 

 stone National Park, Wyo., September, 1903, by J. ffolliott Darling. 



Dlstrihution. — Semi-arid portions of the western United States 

 from southern and eastern Montana and parts of Wyoming west to 

 eastern Oregon and the Sierras of California. 



Intergradation with typical Myotis lucifugus takes place in the 

 Dakotas, and with M. lucifugus alascensis in the Sierras of northern 

 California and in the eastern half of Oregon and Washington. In 

 the mountains of western Montana, two specimens taken at Corvallis 

 are dark enough to be referable to M. I. alascensis^ yet a third is so 

 contrastingly pale and with white-edged membranes as to be typical 

 of M. I. carissima. This individual had perhaps come from a lower 

 level or had wandered in from the south. Not infrequently specimens 

 are found in eastern Oregon or northern California that might, with 

 «qual propriety, be referred to either race, it becoming, therefore, a 

 matter of individual judgment which name shall be given to them. 

 Yet the transition is rather abrupt in most places. Montana speci- 

 mens tend to have a faint trace of the bronze tint characterizing the 

 eastern M. lucifugus lucifugus while those from the northern Sierra 

 Nevada of California have a golden brown cast. As pointed out by 

 Mrs. Grinnell (1918) this bat is chiefly an inhabitant of the forested 

 areas at the higher levels in California, and has been taken at 11,000 

 feet on Mount Whitney at the upper limit of trees. San Bernardino 

 Mountains, Calif., where several specimens were taken at about 7,000 

 feet, represent the southern limit of its range as now known. 



Diagnosis. — Color paler than in Myotis lucifugus lucifugus., the 

 general hue of the upper parts golden instead of bronzy or olive, 

 the belly cartridge buff rather than light chamois; membranes tend- 

 ing to be pale-edged; ears dark; foot larger than in the typical race, 

 the ratio of its length to that of tibia about 55.7. 



Description. — Entire dorsal surface a pale " cinnamon-buff," the 

 hair of the back with long glossy tips which give a more or less 

 golden sheen. Shoulder spot ochraceous tawny ; lower surface a pale 

 buff, very nearly the cartridge buff of Ridgeway. The hairs both 

 above and below have dark blackish-plumbeous bases except at the 

 posterior border of the venter where they are white throughout. 

 Ears, feet, and proximal portion of wing membranes black contrast- 

 ing with the pallid pelage; or in some specimens becoming browner. 

 The edges of the interfemoral membrane and parts of the posterior 

 •edge of the wing membrane may be whitish, sometimes forming a 

 distinct border. 



Measurements. — The dimensions of the type are given b}' Thomas 

 as: forearm 28 mm.; head and body 45; tail 36; ear 13 by 8; third 



