8 University of California Publications in Zoology. |Vou.> 
1905, very hot and glary in the open canon, though the night 
brought a down-canon breeze of refreshing coolness. 
Mountain HOME CANYON. 
A much-used route into the San Bernardino mountains is by 
the way of Redlands, up Mill creek to Skinner’s, and from there 
up Mountain Home ereek, over the divide, and down into the 
upper Santa Ana. Where Mountain Home creek joins Mill 
creek the region is purely Upper Sonoran; but even at Skinner’s 
(elevation 4000 feet), a few hundred yards from the mouth of 
the former, Transition elements begin to appear, and as one fol- 
lows the Mountain Home trail up towards the divide, one after 
another come into prominenee, while Sonoran species are gradual- 
ly left behind. The lower part of Mountain Home canon is lined 
with alders of great height and remarkable straightness and slen- 
derness. This habit of growth is doubtless a result of the deep- 
ness of the ecahon, which means protection from the wind and a 
reaching for the light. Other plants of the lower canon are the 
bay tree, big-leaf maple, golden oak, and big-cone spruce. <As- 
sociated with these are such birds as the western tanager, Califor- 
nia purple fineh, black-chinned hummingbird, Cassin vireo, west- 
ern flycatcher, California yellow warbler, black-throated gray 
warbler, western wood pewee, and olive-sided flycatcher. Further 
up the canon incense cedars begin to appear, and almost simul- 
taneously Sierra juneos become numerous. Soon yellow pines 
are met with, and finally, at the head of the canon, around the 
collection of cabins known as Glen Martin, the woods consist 
chiefly of black oak, yellow pine, sugar pine, and silver fir. In 
this open woods, intermixed with some deer-brush and manzanita, 
a new set of birds are to be seen, as follows: Audubon warbler, 
mountain chiekadee, blue-fronted jay, Cassin purple finch, 
slender-billed nuthateh, and Sierra jJuneo. The gray squirrel is 
a conspicuous mammal. In passing up a graded ascent, such as 
Mountain Home eanon, especially where moisture conditions are 
apparently about the same all the way, the approximate zone 
boundary is impossible to locate even within a mile or more. 
The mergence is slow and gradual. 
