CONTENTS. XI 



Order Rodentia — Continued. 



Family Muridse — Continued. 



Subfamily Cricetinse — Continued. Page. 



Genus Tylomys Peters 179 



Genus Ototylomys Merriam 179 



Genus Nectomys Peters 180 



Genus Rheomys Thomas 180 



Genus Nyctomys Saussure 180 



Genus Sigmodon Say and Ord 181 



Genus Akodon Meyen 186 



Genus Neotomodon Memam 186 



Subfamily Neotominse 187 



Genus Nelsonia Merriam 187 



Genus Teanopus Merriam 187 



Genus Neotoma Say and Ord 188 



Subgenus Neotoma Say and Ord 188 



Subgenus Homodontomys Goldman 199 



Subgenus Teonoma Gray 201 



Genus Hodomys Merriam 203 



Genus Xenomys Merriam 204 



Subfamily Microtinae 204 



Genus Synaptomys Baird 204 



Subgenus Synaptomys Baird 204 



Subgenus Mictomys True 205 



Genus Lemmus Link '. 206 



Genus Dicrostonyx Gloger 207 



Genus Phenacomys Merriam 208 



Genus Evotomys Coues 209 



Genus Microtus Schrank 213 



Subgenus Microtus Schrank 213 



Subgenus Aulacomys Rhoads 224 



Subgenus Pedomys Baird 225 



Subgenus Orthriomys Merriam '. 226 



Subgenus Herpetomys Merriam 226 



Subgenus Chilotus Baird 227 



Genus Lagurus Gloger 227 



Subgenus Lemmiscus Thomas 228 



Genus Pitymys McMurtrie 228 



Genus Neofiber True 229 



Genus Ondatra Link 230 



Subfamily Murinse 232 



Genus Epimys Trouessart 232 



Genus Mus Linnaeus 233 



Family Geomyidse 233 



Genus Thomomys Wied 233 



Subgenus Thomomys Wied 233 



Subgenus Megascapheus Elliot 242 



Genus Geomys Rafinesque 243 



Genus Pappogeomys Merriam 246 



Genus Cratogeomys Merriam 246 



Genus Platygeomys Merriam 248 



Genus Orthogemys Merriam 249 



Genus Heterogeomys Merriam 250 



Genus Macrogeomys Merriam 250 



Genus Zygogeomys Merriam 251 



