TROPICAL NATURE 



development; the forms and colours, of these wonderful little 



bi r( j s if we consider all these varied and complex influences, 



we shall be less surprised at their strange forms, their infinite 

 variety, their wondrous beauty. For how many ages the 

 causes above enumerated may have acted upon them we 

 cannot say ; but their extreme isolation from all other birds, 

 no less than the abundance and variety of their generic and 

 specific forms, clearly point to a very high antiquity. 



The Relations and Affinities of Humming-birds 

 The question of the position of this family in the class 

 of birds and its affinities or resemblances to other groups 

 is so interesting, and affords such good opportunities for 

 explaining some of the best established principles of classifica- 

 tion in natural history in a popular way, that we propose to 

 discuss it at some length, but without entering into technical 

 details. 



There is in the Eastern hemisphere, especially in tropical 

 Africa and Asia, a family of small birds called sun-birds, which 

 are adorned with brilliant metallic colours, and which, in shape 

 and general appearance, much resemble humming-birds. They 

 frequent flowers in the same way, feeding on honey and insects ; 

 and all the older naturalists placed the two families side by 

 side as undoubtedly allied. In the year 1850, in a general 

 catalogue of birds, Prince Lucien Bonaparte, a learned 

 ornithologist, placed the humming-birds next to the swifts, 

 and far removed from the Nectarinidse or sun-birds ; and this 

 view of their position has gained ground with increasing 

 knowledge, so that now all the more advanced ornithologists 

 have adopted it. Before proceeding to point out the reasons 

 for this change of view, it will be well to discuss a few of the 

 general principles which guide naturalists in the solution of 

 such problems. 



How to Determine doubtful Affinities 



It is now generally admitted that, for the purpose of 

 determining obscure and doubtful affinities, we must examine 

 by preference those parts of an animal which have little or no 

 direct influence on its habits and general economy. The value 

 of an organ, or of any detail of structure, for purposes of 



