AMEEICAN BATS OF THE GENEEA MYOTIS AND PIZONYX 41 



Allen collected local forms of both at the same spot by an alpine 

 stream at the limit of trees, 11,000 feet, on Mount Whitney, Cali- 

 fornia. At this locality the animals were probably summer invaders 

 from lower altitudes, M. yumanensis perhaps from the desert at the 

 east base of the Sierra, whence additional examples were later ob- 

 tained. Myotis lucifugus is a social species, breeding in colonies, 

 sometimes in caves, frequently in dark recesses of buildings. It 

 winters in caves in the temperate parts of its range. 



Throughout eastern North America this is by far the commonest 

 species of Myotis^ but in western North America it is less abundant, 

 especially at lower elevations and in desert country. 



In the Eastern Hemisphere Myotis lucifugus is represented by 

 Myotis dauhentonii. The only external characters by which true 

 Myotis dauhentonii and the larger footed forms of M. lucifugus can 

 with certainty be distinguished appear to be that in European 

 specimens {a) the toes are elongated and the claws distinctly en- 

 larged, (6) the insertion of the wing membrane is rather on the basal 

 than the terminal half of the metatarsus, and (c) the fur of the 

 upperparts is not conspicuously glossy and the color of the underparts 

 is more contrastedly paler than that of the back. The skulls of the 

 two species are alike in size and in all essential characters; but in 

 typical M. dauhentonii the dorsal profile from the middle of the 

 brain case backward tends to be evenly convex, while in M. lucifugus 

 there is usually some indication of a concavity at front of occiput, 

 the extreme posterior region tending to rise a little above level of 

 middle of brain case. We have not been able to find any tangible 

 differences between the teeth of the two animals (compare teeth of 

 M. dauhentonii, figured by Miller,^ and those of M. lucifugus, figured 

 by H. Allen ).^ The resemblance betAveen the two species was noted 

 by H. Allen in 1894,^ but we have not seen it mentioned by any other 

 recent author. 



The occurrence of Myotis lucifugus in Kamchatka was recorded 

 by Hahn in 1905® on the basis of a specimen in alcohol (No. \}\l % 

 U. S. Nat. Mus.) collected at Petropavlovsk by Mr. F. Wliymper and 

 brought to Washington by Dr. W. H. Dall. (It was entered in the 

 catalogues Jan. 10, 1873). Another individual, not mentioned by 

 Hahn, was taken by Grebnitzki at the same i^lace in July, 1889 

 (No. 155523 U. S. Nat. Mus.). Both specimens are in poor condition 

 and neither of them has a perfect skull. After careful examination 

 we are unable to distinguish them, on the basis of the characters 



" Cat. Mammals Western Europe, Brit. Mus., p. 186, Nov. 23, 1912. 



•Monogr. Bats North Amer. (1893), pi. 11, Mar. 14, 1894. 



■* Monogr. Bats North Amer., p. 79. 



■ Proc. Biol. Soe. Washington, vol. 18, p. 254, Dec. 9, 1905. 



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