2 r4 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 Troohilidae, 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- 

 lieving that very many more — not less perhaps 

 than one or two hundred species — yet remain to be 

 discovered. The most prolific region, and where 

 humming-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 



