Revision of taxonomy necessary The classification list at the top insinuates that all mice belong to the genus Mus but there are many genera of mice Chaetodipus Zapus Napaeozapus Onychomys Baiomys Ochrotomys Peromyscus Reithrodontomys Oryzomys Liomys Micrdipodops and Perognathus all live in the United States alone Whitaker 1991 I couldn t even guess how many genera there must be in total Mus only accounts for a miniscule portion of the richness and diversity of the animals we call mice It should be noted as well that mice are a polyphyletic grouping since some mice are more related to some rats for instance than they are to other mice citation Whitaker John O Jr The Audubon Society Field Guide to North American Mammals pub Knopf Alfred A Inc ISBN 0 394 50762 2