LEPORIDZ—GEOGRAPHICAL DISTRIBUTION. 275 
the damp, heavily-wooded region of British Columbia and Washington and 
Oregon Territories. 
In the interior, we meet next with Lepus campestris, which ranges over 
the treeless region from the Saskatchewan Plains southward to about the 
latitude of Middle Kansas, or mainly between the isotherms of 36° and 56°. 
Each of the three above-named species becomes more or less white in 
winter, and they are the only species which thus change. The whiteness of the 
winter pelage extends to the very base of the fur in the more northern spe- 
cies, but generally affects only the more superficial portions in the others, 
the whiteness decreasing to the southward in the representatives of the 
LL. americanus group (excepting var. Bairdiz), till in the extreme southern 
portions of the habitat of this species the change occurs merely at the surface. 
In L. campestris, the change is still less complete, decreasing similarly in 
extent southward, till in the extreme southern portion of its range the change 
fails to be universal, and rarely extends throughout the pelage, being confined 
mainly to a limited portion of the dorsal aspect. 
The habitat of Lepus sylvaticus (including its several varieties) extends 
from Southern New England on the Atlantic coast southward to Yucatan, 
its representatives nowhere presenting marked seasonal changes of color. 
Throughout this vast extent of latitude, it also preserves a remarkable con- 
stancy of characters. From the Atlantic coast westward (south of the 
isotherm of 45°) to the eastern edge of the Great Plains, it is represented 
solely by variety sylvaticus. Here it passes by imperceptible stages into 
variety Muttalli (= artemisia auct.), which ranges thence westward nearly 
or quite to the Pacific coast north of the State of California. To the south- 
ward of this boundary, it is replaced, on the Pacific slope, by its nearly 
related variety Auduboni, and over the Great Colorado Desert becomes 
modified into another closely-allied form, to which we have given the name 
var. arizone. Variety Nuttalli ranges southward from the isotherm of 45° 
to the plains of Western Texas and New Mexico, and even as far south as 
the arid Mexican plateau. Variety arizone seems confined to the limited 
region of the almost rainless deserts of Arizona and Southern California, or 
the so-called Sonoran district. Variety Auduboni occupies the Pacific slope 
from the northern boundary of California southward to Cape Saint Lucas, 
and in the interior seems to gradually pass into var. avizone. 
The Sierra Nevada Mountains seem also to form a barrier to the east- 
