NORTH AMERICAN" LAND MAMMALS. 225 



t*Microtus richardsoni macropus (Merriam) . 



1891. Arvicola (2[ynomes) macropus Merriam, North Amer. 



Fauna, No. 5, p. 59. July 30, 1891. 

 1900. Microtus richardsoni macroims Bailey, North Amer. 



Fauna, No. 17, p. 61. June 6, 1900. 

 Type Locality. — Pahsimeroi Mountains, Idaho. Altitude, 



about 9,700 feet. 

 Range. — Boreal zone of the Rocky Mountains from the Wasatch 



north to Canada, of the Wind River Mountains of Wyoming, 



the Blue Mountains of Oregon, and most of the intermediate 



ranges. 



*Microtus richardsoni arvicoloides (Rhoads). 



1894. Aulacomys arvicoloides Rhoads, Amer. Nat., vol. 28, 

 p. 182. February 11, 1894. 



1895. Microtus principalis Rhoads, Amer. Nat., vol. 29, p. 940. 

 October, 1895. (Mount Baker Range, British Columbia.) 



1900. Microtus richardsoni arvicoloides Bailey, North Amer. 



Fauna, No. 17, p. 62. June 6, 1900. 

 Type Locality. — Lake Keechelus, Kittitas County, Washington. 



Altitude, 8,000 feet. 



Range. — Boreal zone of the Cascade Mountains, in Washington 



and Oregon. 



Subgenus Pedomys Baird. 



1857. Pedomys Baird, Mamm. N. Amer., p. 517. Type, 

 Arvicola austerus LeConte = Hypudseus ochrogaster Wagner. 



*Microtus ochrogaster (Wagner). 



1842. Ilypudxus ochrogaster Wagner, Schreber's Saugthierc, 

 SuppL, vol. 3, p. 592. 



1885. Arvicola austerus True, Proc. U. S. Nat. Mus., vol. 7 

 (1884), p. 597. 1885. 



1898. Microtus ochrogaster Allen, Bull. Amer. Mus. Nat. Hist., 

 vol. 10, p. 458. November 10, 1898. 



1907. Microtus ochrogaster Osgood, Proc. Biol. Soc. Washington, 

 vol. 20, p. 48. April 18, 1907. 



Type Locality. — America. 



Range. — Central part of Mississippi Valley from southern Wis- 

 consin to southern Missouri and Fort Reno, Oldahoma, and 

 west into eastern Nebraska and Kansas. 



t*Microtus ludovicianus Bailey. 



1900. Microtus ludovicianus Bailey, North Amer. Fauna, No. 17, 



p. 74. June 6, 1900. 

 Type Locality. — Iowa, Calcasieu Parish, Louisiana. 

 Range.— Coast prairie of southwestern Louisiana, m lower 



austral zone. 



43900°— Bull. 79—12 15 



