520 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 45. 



Three specimens. Two of these were trapped under thorn bushes 

 on the dry, semi-desert hills near Ust-Inya, at 3,850 feet, June 24, 

 and one was captured at the Tapucha canip in heavy forest border- 

 ing open alps at 6,875 feet, August 8. The species was evidently 

 a common one at Ust-Inya, as several examples, either ruined by 

 the trap or very immature, were caught in the one night's trapping, 

 in addition to those saved. At Tapucha this little mouse occurs 

 with the much larger and differently colored Apodemus nigritdlus, 

 but it seemed by no means as abundant as the latter species. With 

 these specimens, and a good series of the larger species from the 

 Altai before me, it is plain that Kastschenko's original descrip- 

 tion of Mus tsclierga relates wholly to this, the smaller, species. 

 Later * Kastschenko received an additional collection from the 

 Altai which contamed specimens of the larger species, and assum- 

 ing that these were the adults of the species previously named 

 tsclierga, he proceeded to rediagnose his form. The young of the larger 

 species, of a size about equal to the adults of the smaller tsclierga, 

 have the hind foot always 22 mm. or more, or about as in the fully 

 grown (hind foot of adults of A. nigHtalus measures 22 to 25 mm.), 

 while the adults and immature of tsclierga have a hind foot measure- 

 ment of 19 or 20 mm. The form described by Miller from Russian 

 Turkestan ^ as Apodemus microtis seems indistinguishable from 

 Apodemus sylvaticus tsclierga. 



1 See Ann. Mus. Zool. St.-P6tersbourg, vol. 7, 1902 , p. 301. 



2 Proc. Biol. Soc. Washington, vol. 25, p. 60, April 13, 1912. 



