214 The Naturalist in La Plata. 
not proceed in that methodical manner which bees 
follow, taking the flowers seriatim, but skip about 
from one part of a tree to another in the most 
capricious manner.’ I have observed humble-bees 
a great deal, and feel convinced that they are 
among the most highly intelligent of the social 
hymenoptera. Humming-birds, to my mind, have 
a much closer resemblance to the solitary wood- 
boring bees and to dragon-flies. It must also be 
borne in mind that insects have very little time in 
which to acquire experience, and that a large 
portion of their life, in the imago state, is taken up 
with the complex business of reproduction. 
The Trochilide, although confined to one con- 
tinent, promise to exceed all other families—even 
the cosmopolitan finches and warblers—in number 
of species. At present over five hundred are 
known, or as many as all the species of birds in 
Europe together; and good reasons exist for be- 
heving that very many more—not less perhaps 
than one or two hundred species—yet remain to be 
discovered. ‘The most prolific region, and where 
hummine-birds are most highly developed, is known 
to be West Brazil and the eastern slopes of the 
Bolivian and Peruvian Andes. This is precisely 
the least known portion of South America; the 
few naturalists and collectors who have reached it 
have returned laden with spoil, to tell us of a 
region surpassing all others in the superabundance 
and beauty of its bird life. Nothing, however, 
which can be said concerning these vast unexplored 
areas of tropical mountain and forest so forcibly 
impresses us with the idea of the unknown riches 
