MURIDA. — CLKXXV. 321 
and hind feet; tail longer. L.5. T. 4. Lowland swamps, Va, 
especially the Dismal Swamp. (€Aos, swamp ; dAjrns, wanderer.) 
544, MICROTUS Schrank. (Fre~p Mice.) (wexpos, small; 
ovs, ear.) 
a. Posterior upper molar with one exterior triangle and a posterior trefoil; 
middle upper molar with one internal triangle; front lower molar with 
two internal and one external triangle. 
b. Fore claws larger than hinder; fur dense, silky, mole-like ; size small. 
(Pitymys McMustrie.) 
1043. M. pinetorum (Le Conte). Pine Mouse. Chestnut 
color, ashy below. L.4%. T.4. Mass. toIll.andS, The northern 
form is subspec. scalopsoides (Aud. & Bach.). (Lat., of the pines.) 
bb. Foreclaws not larger than hinder; fur coarse, not glossy; size medium. 
(Pedomys Baird.) 
1044. M. austerus (Le Conte). Prarrir Meapow Mouse. 
Grizzly brownish, rusty plumbeous below. L. 5. T.1. Mich. to 
Kan., and S. (Lat., harsh.) Subspec. minor (Merriam) occurs 
in Minn, and Dak. 
1045. M. cinnamomeus (Baird). Similar to M. austerus, the 
skull narrower ; yellowish brown above with rufous wash ; belly pale 
cinnamon; tail bicolor. L. 44. T. 13. Minn. (Lat., cinnamon.) 
aa. Posterior upper molar with two external triangles and a posterior cres- 
cent ; middle upper molar with two internal triangles; front lower molar 
with three internal and two or three lateral triangles; size large. 
( Microtus.) 
1046. M. pennsylvanicus (Ord). Mrapow Mouvusr. Fore 
claws not longer than hind claws. Grayish brown, blackish me- 
sially, hoary below. L. 53. T. 14. E. U. S., generally abundant; 
variable. Subspec. fontigenus (Bangs) from localities in Canada, 
and subspec. acadicus from Nova Scotia, have been described. 
1047. M. chrotorrhinus (Miller). Slightly smaller than 
M. pennsylvanicus with broader hind feet; nose patch tawny ochra- 
ceous; brain case low, broad. White Mts.,N.H. (xpés, color ; 
piv, nose.) 
1048. M. breweri (Baird). Size of Mf. pennsylvanicus, or larger, 
paler, yellowish gray, below nearly white. Muskeget Island, Mass. 
(To Dr. T. M. Brewer.) 
545. EVOTOMYS Coues. (RED-BACKED VOLES.) (ed, well; 
ous, ear; pis, Mouse.) 
1049. B. gapperi (Vigors). Rep-Backep Voir. Median line 
of back bright chestnut; sides buffy-ochraceous; belly pale buffy 
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