MICROTUS. 107 



294. ludovicianus. {Mu-rotus), Bailey, N. Am. Fauna, No. 17, 1900, 



P- 74- 



Type locality. Iowa, Calcasieu Parish, Louisiana. 



Geogr, Dislr. Coast prairie, southwestern Louisiana. 



Genl. Char. Similar to .1/. austerus; rostrum and nasals more 

 slender; bulla larger. 



Color. Above dark gray; beneath fulvous ; tail dusky above, 

 buffy beneath; feet dusky. 



Measurements. Total length, average two adults, 164; tail verte- 

 brje, 33; hind foot, 18.5. 



295. haydeni. {Arricola), Baird, N. .\m. Mamm., 1857, p. 543. 

 T\pe locality. Fort Pierre, South Dakota. 



Gec'xr. Distr. Fort Pierre and the Black Hills, South Dakota, 

 to the North Platte River, western Nebraska; eastern Colorado and 

 Wyoming, and southern Montana. 



Genl. Char. Larger than M. austerus; tail not twice the length 

 of hind foot; ears short, half as long as hind foot; soles hairy for 

 half the length; last upper molar with two interior and one exterior 

 triangle. 



Color. Above gray yellowish brown mixed with black ; sides 

 grayer and less black; beneath grayish yellowwhite, tinged with pale 

 yellowish rusty. Feet pale rusty yellowish white. Tail above brown, 

 beneath pale yellowish rusty. 



^feasurements. Total length, 153-180; tail vertebrae, 3S-47; hind 

 foot, 20-22. 



296. minor. {Arvicola), Merr., Amer. Nat., 1S88, p. 600. 

 Ty/e locality. Bottineau, Turtle Mountain, North Dakota. 

 Geogr. Distr. From Edmonton, Alberta, to northwestern North 



Dakota, and southeastwardly to Minneapolis, Minn. 



Genl. Char. Similar to .)/. austerus; smaller. 



Color. Above grizzled gray, beneath whitish washed w'ith cin- 

 namon. Tail bicolor, dusky above, buffy beneath. Feet gray. 



Measurements. Totallength, 133; tail vertebra", 36; hind foot, 16.5. 



D. PitTmys. 



Palate normal; lower third molar without closed triangles, but 

 with three transverse loops; lower first molar with three closed and 

 two open triangles and nine salient angles; upper third molar with 

 two closed triangles and six salient angles. Mammae, 4 inguinal; 

 plantar tubercles, 5; soles hairy. 



