REVISION OF THE JUMPING MICE OF THE GENUS ZAPUS. 39 



The largest is so badly crushed as to be almost worthless, and the two 

 smaller ones lack the occipital portion of the cranium and the posterior 

 parts of the mandibles, the shape of the angular process, therefore, 

 being unknown. This species has the small upper premolar as in the 

 subgenus Zapus, that tooth being larger than in Z. hudsonius. The last 

 lower molar is also proportionately larger. All the molars difl'er from 

 those of any American species in having the enamel folds not closely 

 crowded, the resulting wide and deep sulci giving the teeth a very 

 different appearance, though the general pattern of enamel folding is 

 perhaps not essentially different. The incisors are lighter in color 

 than in the American species. 



Specimens examined. Two skins and three skulls, from the type 

 locality. 



