654 NATURAL HISTORY OF THE VALLEY OF QUITO. 
boldt says: ‘‘' The character of the flora of the elevated plateaux 
of Mexico, New Granada and Quito, of European Russia and of- 
Northern Asia, consists, in my opinion, not so much in the rela- 
tively larger number of species presented by one or two natural 
families, as in the more complicated relations of the coexistence 
of many families and in the relative numerical value of their spe- 
cies.” 
The flora of islands and highlands are strikingly akin in their 
present features and also in their origin. Both resulted from 
migration, for since the great mountain chains are recent up- 
heavals, evidently our Alpine plants must be only altered forms of 
lowland species. 
The flora of Quito has some bearing on the question of a glacial 
winter within the tropics. The identity of many plants on moun- 
tain summits, separated from each other by hundreds of miles of 
lowlands where the Alpine species could not possibly exist, is well 
known. The peaks of the Alps and Pyrenees show a number 0 
plants like those in Lapland, but nowhere found in the intervening 
plains. The flora of the top of Mount Washington is identical 
with that of Labrador. Mr. Wallace tells us that the isolated vol- 
cano of Pangerango, in Java (which has the same latitude and 
altitude as Quito), presents a vegetation closely allied to that of 
Europe, and Forbes has shown that the mollusca of Britain mi- 
the New World it would follow that by the time the cold 
reached its maximum, the now temperate regions of pager 
States would be covered by an arctic flora, while the plants indig 
enous to the latitude of New York would be driven into or” 
and the Isthmus;—as when our winter creeps down from ' 
. ; Te- 
north, our summer birds travel southward. As the warmth 
perate plants, unable to bear the returning 
lowlands, would scatter,—many species returning t 
northern quarters, some of which could not survive , 
perishing utterly, and others, naturally seizing upon the 
