4 
BOMBYCES. 
Amazon Valley and the northern ranges of the Andes, southward to Southern Brazil, the number of forms 
diminishing first slowly, then with extraordinary rapidity, until in the still temperate region between 35° and 40° 
latitude mere fragments are encountered; one might say that nowhere on earth do the Lepidoptera decrease 
from a superabundance of forms so markedly and suddenly as in America between 30° and 35° latitude; and 
this is the case not only in South Chile, which is very poor in Lepidoptera, but also throughout Eastern Patagonia, 
a quite different open landscape. To find an adequate reason for this peculiar phenomenon is less easy than for 
another fact, viz., that the Bombyces and Sphinges are as good as extinct in Southern Patagonia; the fact 
alone that nearly all higher plants have been suppressed by the Cryptogamic flora, which fourishes here, is 
sufficient to account for the disappearance of all Bombyces and Sphinges, these being absolutely dependant 
on Phanerogams. 
