55 Bulletin American Museum of Natural History. [Vol. XIX, 



measure as follows: 7 males, total length, 151 (146-162); 

 tail vertebrae, 41.3 (40-46); hind foot, 18.4 (18-19); ear > I2 -7 

 (12-13): 5 females, 155 (153-158); 42 (40-44); 18.6 (18- 



19-5); i3- 2 (i3-!4). 



There is a wide range of individual variation in color, both 

 July and September specimens varying above from a dark 

 gray brown, slightly suffused with yellowish brown, to darker 

 brown strongly suffused with chestnut; the underparts may 

 be pure gray or strongly washed with buffy, especially in fall 

 specimens after the moult. 



It is of interest to note that 30 of the 39 specimens of this 

 species were taken on Level Mountain and only one at Tele- 

 graph Creek; while in the case of M. m. vellerosus 38 out of 52 

 specimens were taken at Telegraph Creek, and only 6 on 

 Level Mountain, showing that the two forms occupy different 

 areas of abundance. 



My Microtus stonei (this Bulletin, Vol. XII, 1899, p. 5), 

 based on a specimen from the head of Liard River, is unrepre- 

 sented in the present collection. The present large series of 

 M. drummondi, together with a series of over 20 specimens 

 from northern Alberta, furnish ample means for the compari- 

 son of M. stonei with M. drummondi. Instead of "the type 

 of M. stonei" being "indistinguishable from typical drum- 

 mondi" (cf. Bailey, N. Am. Fauna, No. 17, 1900, p. 23), it 

 proves to be cranially widely different, although externally 

 closely resembling drummondi. In M. stonei the rostral por- 

 tion of the skull, including the interorbital region, is very 

 narrow and greatly elongated, in strong contrast to the short, 

 broad form of this portion of the skull in M. drummondi, and 

 the incisive foramina are correspondingly long and narrow. 

 In stonei the superior aspect of the interorbital region has also 

 a deep longitudinal groove never present in drummondi; and 

 the maxillary branch of the zygoma is much narrower; the 

 angular process of the lower jaw is longer, slenderer, and more 

 pointed. The form of the posterior loop of the last upper 

 molar is also distinctly different. M. stonei may therefore 

 be regarded as specifically distinct from M. drummondi. 



