Perognathus spinatus Merriam Spiny Pocket Mouse 

 With a light stripe along each side 102. 



102. Front edge of ear only onc'fourth as long as the hind foot; Cal. 



Perognathus fallax Merriam Short-cared Pocket Mouse 

 Front edge of ear about onc'third as long as the hind foot; N. M. and 

 Ariz. 



Perognathus intermedius Merriam Intermediate Pocket Mouse 



103. In the northern plains to Colo. 104. 

 In the Rocky Mountain and Pacific states 106. 



104. Under parts huffy 



Perognathus fasdatus Wied Maximillian Pocket Mouse 

 Under parts white 105. 



105. Fur soft; Wyo. southwards 



Perognathus fiavus Baird Baird Pocket Mouse 

 Fur coarse; northern plains 



Perognathus fiavescens (Merriam) Plains Pocket Mouse 



106. Small; total length of adult less than six inches 107. 

 Larger; over six inches in adult specimens 110. 



107. Tail about two and one-half to three inches long, about as long as head 



and body; often with a light lateral stripe 108. 



Tail about two inches long, shorter than head and body; light lateral 



stripe obscure or absent 109. 



108. Ears large; Utah to Cal. 



Perognathus longimemhris (Coues) Fort Tejon Pocket Mouse 

 Ears small; Colo, to Ariz. 



Perognathus apache Merriam Apache Pocket Mouse 



109. Tail with very little hair; Texas and N. M. 



Perognathus merriami Allen Merriam Pocket Mouse 

 Tail with moderate amount of hair; Wyo. southward 

 Perognathus flavus Baird Baird Pocket Mouse 



110. Tuft at end of tail over one-half inch long; Utah to Cal. 



Perognathus formosus Merriam Long-tailed Pocket Mouse 

 Tuft at end of tail less than three-eighths of an inch long 111. 



111. In central and southern Cal. 



Perognathus inornatus Merriam San Joaquin Pocket Mouse 

 From northern Cal. to Wash, and Idaho 



Perognathus parvus (Peale) Oregon Pocket Mouse 



112. Tail about one and one-half times as long as head and body; hind legs 



very long; fore legs short; Family Zapodidae Jumping Mice 113. 



Tail not much longer than head and body, usually shorter; hind legs not 



greatly lengthened 118. 



113. With a white tip to the tail; only three grinding teeth in each side of the 



upper jaw; eastern and central states 



J^apaeozapus insignis (Miller) Woodland Jumping Mouse 

 No white tip to tail; usually four grinders in each side of upper jaw, the 

 first very small 114. 



515 



