498 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. III. 



PAGE. 



304. Microtus curtatus. (Cope.) 195 



305. Microtus pallidus. (Merr.) 195 



0. Pedomys. 



306. Microtus austerus. (Le Conte.) 196 



307. Microtus ludovicianus. Bailey 197 



308. Microtus haydeni. (Baird.) 197 



309. Microtus minor. (Merr.) 197 



D. Pitymys. 



310. Microtus pinetorum. (Le Conte.) 198 



Microtus pinetorum scalopsoides. (Aud. and Bachm.). . . 198 



Microtus pinetorum auricularis. Bailey 198 



311. Microtus nemoralis. Bailey 199 



E. Ohilotus. 



312. Microtus oregoni. (Bachm.) 200 



313. Microtus serpens. (Merr.) 200 



314. Microtus bairdi. Merr 200 



P. Arvicola. 



315. Microtus richardsoni. (De Kay.) 200 



Microtus richardsoni macropus. (Merr.) 201 



Microtus richardsoni arvicoloides. (Rhoads.) 202 



G. Neofiber. 



316. Microtus alleni. True 203 



56. Synaptomys. Baird, 1857. 



A. Synaptoinys. 



317. Synaptomys cooperi. Baird 203 



Synaptomys cooperi* gossi 204 



318. Synaptomys fatuus. Bangs 204 



319. Synaptomys helaletes. Merr 204 



B. Mictomys. 



320. Synaptomys innuitus. True 205 



Synaptomys innuitus medioxinus. Bangs 430 



*This. being a western form, would seem to be more properly a subspecies of S. cooperi, 

 which extends its range from the Atlantic coast to Iowa, than to be associated with S. helaletes^ 

 only known from the Dismal Swamp, Va., as Dr. Merriam has arranged it. 



