506 Miscellaneous Intelligence. 
teristic of immense areas of the continent. There are two tem- 
the two latter of widely different origin, and in one sense proper 
to the Rocky Mountain ranges. 
The principal American regions with which the comparison will 
have first to be instituted are four. Two of these are in a broad 
sense humid; one, that of the Atlantic coast, and which extends 
thence west to the Micsissipp! River, including the forested shores 
of that river’s western affluents ; the other that of the Pacific side, 
from the Sierra Nevada to the western ocean: and two inland, 
that of the northern part of the continent anette to the Polar 
regions, and that of the southern part extending ‘through New 
Mexico = the Cordillera of Mexico proper. 
t and second (Atlantic plus Mississippi and the Pacific) 
teatime of are traversed by meridional chains of mountains approxi- 
mately parallel to the etks Mountains; namely, on the Atlantic 
side by the various pore a — under oe cee te term 
t 
tending from the Snake River to Arizona and Mexico. Thus the 
Colorado and Utah floras might be expected to contain represent- 
atives of all the various vegetations of North America except the 
small tropical region of oo which is confined to the extreme 
southeast of the Continen 
e most singular breach aeergein * are America is un- 
questionably the marked cont between its two humid floras, 
peaiet Se those of the “Atlantic ies nw: and the Pacific one ; 
his has been ably illustrated and discussed by Dr. Gray in vari- 
ous communications to the American Academy of Sciences, and 
elsewhere, and he has further largely traced the peculiarities of 
each to their source, thus laying the eee BTS for a fat ture re- 
ssing. 
Our course and direction in ice as cermers westward to 
Colorado, where we followed the ostionn flanks of the Rocky 
Monntains for about 300 miles, that i s fro om Denver i in the north, 
