14 NORTH AMERICAN FAUNA. 



Subgeuus Xapa'ozapus. 



abietorum nob. Peninsula Harbor, Ontario. 



insiynis. Restigouche River, New Brunswick. 



roanensis nob. Magnetic City, Roan Mountain, North Carolina. 



Subgenus Eozapus. 

 setchuanus. ' Ta-tsieu-lou, Szechueu, China. 



Subgenus ZAPUS Coues. 



Type Zapus hudsonius (Zimmermanu), from Hudson Bay. 



Subgeneric characters. Teeth: i. ^, p. ^, m. |5j = 18. Upper pre- 

 molar very small, nearly cylindrical ; anterior upper molar large, broadly 

 oval; in 2 similar, bat noticeably smaller; m 3 con- 

 siderably smaller and nearly circular. Lower 

 molars similar in shape and relative size (tig. 1). 

 Enamel folds closely crowded. Interorbital con- 

 striction of medium width; frontal region inoder- 

 FIG. i. Molar teeth of ately swollen ; brain case rather high; rostrum 

 zap us AtMbonitu from s i eu( i er and somewhat attenuated. 



Tower, Minnesota (No. 



72695, u. s. Nat. MUS.) Upper partsas m entire genus; lower parts white, 

 x 6 - sometimes suffused with color of sides; tail more or 



less distinctly bicolor, normally without white tip. 



KEY TO SPECIES OF THE SUBGENUS ZAPUS. 



Lower parts much suffused with color of sides orarius. 



Lower parts not much suffused with color of sides. 

 Size, large; hind foot usually more than 32 mm. 

 Ears never conspicuously bordered with whitish. 



Larger; pencil of tail never normally white ; lower parts often suffused with 



ochraceous tnnotatus. 



Smaller; pencil of tail usually white; lower parts never suffused with 



ochraceous alleni. 



Ears usually conspicuously bordered with whitish. 



Sides light ochraceous buff nevadensis. 



Sides not light ochraceous buff. 



Skull narrow ; incisive foramina very large solicitor. 



Skull broad ; incisive foramina not very large. 



Hind foot about 35 mm major. 



Hind foot about 32 to 34 mm. 



Incisive foramina broad posteriorly orer/onus. 



Incisive foramina narrow posteriorly princcps. 



Size medium or small; hind foot usually below 32 mm. 



Size medium; hind foot 30 to 32 mm. ; total length of adults more than 215 

 mm. 

 Skull rather heavy ; brain case broad; incisive foramina rather large. 



Dorsal area not very distinct pacijicits. 



Dorsal area distinct. 



Rostrum considerably deflected minor. 



Rostrum not much deflected .. .. montanm. 



