CONTENTS. 



Paga 



Introduction 5 



History and material 5 



Distribution 6 



External characters 7 



Habits 7 



Nomenclature 9 



Generic names 9 



Specific and subspecific names 10 



Genus Zapus Coues . 13 



Key to subgenera 13 



List of species and subspecies, with type localities 13 



Subgenns Zapus Cones 14 



Key to species 14 



Napceozapus subgenus novuin 33 



Key to species 33 



Eozapus subgeuus no vuui 37 



ILLUSTRATIONS. 



PLATE. 



Page. 

 PLATE I. Skulls of Zapus insignia, Z. setcliuanus, Z. hiulsonius, Z. orariu*. 



Z, trinotatus, and Z. princeps 42 



TEXT FIGURES. 



FIG. 1. Molar teeth of Zapus hudsonius 14 



2. Molar teeth of Zapus insignia 33 



3. Molar teeth of Zapus setchuanus 37 



4. Skull of Zapus setchuanus 38 



