X Illustrations 
FIG. PAGE 
12. Great Plains Jack Rabbit, Lepiis c. melanotis, 
dorsal view of skull ..... 42 
13. Great Plains Jack Rabbit, Lepiis c. melanotis, 
skull, showing dentition .... 42 
14. Young Cottontail Rabbit . . . .46 
15. Rocky Mountain Cottontail, Sylvilagus n. 
pinetis ....... 48 
16. Wyoming Cottontail, Sylvilagus a. bailey i, 
dorsal view of skull ..... 50 
17. Wyoming Cottontail, Sylvilagus a. baileyi, 
in form . . . . . . .51 
18. Cony or Pika 55 
19. " Hay Pile " of Cony ..... 56 
20. Yellow-haired Porcupine, Erethizon epixanthum, 
skull, showing dentition . . - - 57 
21. Yellow-haired Porcupine, Erethizon epixanthum, 
on tree ....... 59 
22. Yellow-haired Porcupine, Erethizon epixanthum, 
on tree ....... 60 
23. Rocky Mountain Jumping Mouse, Zapus prin- 
ceps, skull, showing dentition ... 63 
24. Rocky Mountain Jumping Mouse, Zapus prin- 
ceps ........ 64 
25. Plains Pocket Mouse, Perognathus flavescens, 
skull, showing dentition .... 68 
26. Moki Kangaroo Rat, Perodipus longipes, skull, 
showing dentition ..... 72 
