MICROTUS. 101 



Co/or. Similar to .U. townsendi. Above grizzled blackish brown; 

 below ash; feet grayish brown: tail above like back, below like under 

 parts. 



.\f,i.isnr,nunls. Total length, 170; tail vertebrae, 50; hind foot. 23. 



281. longicaudus. {Arvicola), Merr. Amer. Nat., 1888, p. 934. 

 Type- locality. Custer, Black Hills, South Dakota. 

 Geogr. Distr. Western South Dakota, Wjoming. 



Genl. Char. Antitragus closing like meatus; tail verj' long. 



Color. Above and sides bister, grizzled with rusty on back; sides 

 grayish, beneath buffy gray; feet plumbeous ; tail blackish above, 

 whitish beneath. 



.Veasurements. Total length, 185; tail vertebra?, 65; hind foot, 21. 



282. mordax. (Arvicola), Merr., N. Am. Faun., No. 5, 1891, p. 61, 



pi. II, fig. 3-4. 



vellerosus, Allen, Bull. Am. Mus. Nat. Hist., 1899, p. 7. 



cautus, Allen, Bull. Am. Mus. Nat. Hist., 1899, p. 7. 



Type locality. Sawtooth or Alturus Lake, east foot of Saw- 

 tooth Mountain, Idaho. 



Geogr. Distr. " In Rocky Mountains and contiguous ranges 

 from latitude 60 to northern New Mexico, and in the Cascades of 

 Sierra Nevada to Kaweah and Kern rivers, California." 



Genl. Char. Similar to M. longicaudus, but larger; tail longer, 

 ears smaller; skull with processes and ridges more developed than in 

 allied species. 



Color. Above pale grayish bister, lined with black; sides clear 

 gray; under parts and feet whitish. Tail dark above, whitish below; 

 feet plumbeous. 



Measurements. Total length, 200; tail vertebra-, 77; hind foot, 

 22; ear, 10. 



283. macrourus. {Microtiis), Merr., Acad. Nat. Scien. Phil., 1898, 



P- 353- 



Type locality. Lake Cushman, Olympic Mountains, Washington, 



Geogr. Distr. Olympic Mountains, northwest Washington, and 

 Alaska to Yakutat. 



Genl. Char. Similar to ^f. monla.v, but larger; tail longer; hind 

 feet larger; color darker. 



Color. Above brownish bister, grizzled; sides paler; beneath 

 whitish, base of hairs plumbeous; tail dusky above, whitish below; 

 tip sometimes white. Feet plumbeous. 



A/easurements. Average total length, 204; tail vertebrae, 80; 

 hind foot, 24. Type specimen: Total length, 220; tail vertebrae, 88; 

 hind foot, 24.3. 



