4^ Th^ Mammals of Colorado 
The posterior portion of the postorbital process is slender and 
tapering and lying quite well away from the skull, leaving a good- 
sized foramen; anterior portion of process quite short and slender, 
making only a narrow notch with the skull; bullae small and 
smooth. 
The two species whose ranges touch and overlap that of S. 
pinetis are baileyi and warreni. From either one it may be dis- 
tinguished by its shorter ear, smaller bullae, and narrower postorbi- 
tal processes. It is almost always darker and ruddier than baileyi, 
and while often dark and blackish, has never the black look that so 
many specimens of warreni have. 
FIG. 15. ROCKY MOUNTAIN COTTONTAIL, Sylvilagiis 71. pinetis 
E. R. Warren, Photo. 
Distribution. — The Rocky Mountain Cottontail is found from 
central Arizona and middle western New Mexico north through 
Colorado, except the northwest corner. As its name indicates, 
it is an inhabitant of the mountains rather than the plains, and has 
been recorded in Colorado, from the higher parts of Larimer, 
Boulder, Jefferson, El Paso, Teller, Chaffee, Custer, Conejos, 
Costilla, Mineral, Saguache, Grand, Gunnison, Huerfano, La Plata, 
