])nj'n1ivoly Imnnlc'ss l)()1li to iiu^adovvs mihI to j^i'ains Miid voi?('ta])]os. 

 However, 1 know ol' no way in wliieli it is useful unless it be in 

 destroying a few weed scH'ds and an occasional insect. When it 

 enters grain fields it may do considerable damage and it is always 

 to be considered a pest that should be suppressed rather than a 

 species to be protected. 



MICROTUS OCHROGASTER (Wagner). 

 PRAIRIE VOLE. 



Arvicola ochrogastcr Wagner, Suppl. to Schreber's Saugethiere, 



Vol. Ill, p. 592, 1843. 

 Af^vicola austerus Le Conte, Proc. Acad. Nat. Sci. Phil., Vol. 



VI, p. 405, 1853. Baird, Mammals N. Am., p. 539, 1857. 



Evermann and Butler, Proc. Ind. Acad. Sci. for 1893, p. 



121. 



Microtus austerus Bailey, N. A. Fauna, No. 17, p. 73, 1900. 

 Microtus ochrogaster Osgood, Proc. Biol. Soc, Wash., Vol. XX, 

 p. 48, 1907. 



Diagnostic characters. — Distinguished from other Indiana voles 

 by the "salt and pepper" color of the fur of the back and the 

 ''ochery yellow" tinge which overlies the hair of both back and 

 belly; size medium; tail one to one and a half inches. 



Description. — Fur of back plumbeous at base, the long coarse 

 hairs being dark throughout their entire length while the shorter 

 fur is banded with black and gray or buffy. Sometimes the pale 

 band is decidedly brownish and the animal resembles M. pennsyl- 

 vanicus slightly. The sides are paler and the hairs of the belly 

 lack the black bands, but are plumbeous at the base and gray or 

 fulvous at the tips. There is considerable variation in the color and 

 certain specimens from Laporte in the collection of the Field ]\Iu- 

 seum have less of the yellow tinge than most of those from south- 

 ern Indiana. I am unable to state, however, that these differences 

 are more than individual variations. The tail is slender, the same 

 color as the back above and very nearly white below. Feet pale; 

 a yellowish ring about the eye in most individuals. 



Measurements. — Ten specimens from Mitchell average as fol- 

 lows: Total length, 143.6 mm (5 12/16 in.); tail, 35.7 mm. 

 (1 7/16 in.) ; hind foot, 19.7 mm. (13/16 in.). 



Skull and teeth. — The skull (fig. 10) is long, narrow and round- 

 ed as compared with other species of Microtus. The molars (fig. 

 8c) have wide spreading, re-entrant angles. The first lower molar 



