INTRODUCTION. xiii 



The hinomial name will probably generally be used as a contraction ; but 

 it must never be forgotten that it is only a contraction. The difference 

 between a species and a subspecies, though in some cases not very clear, 

 IS far too important a fact to be sacrificed to a craze for a uniform 

 binomial nomenclature. 



The grouping of individuals into subspecies and species is the first 

 step in 



The Classification of Birds. 



The second step is to group species into genera and subgenera ; the third 

 is to group genera into families and subfamilies, and the fourth to group 

 families into orders and suborders. The use of the terms subspecies, 

 subgenera, &c. implies that all these divisions and subdivisions are more 

 or less artificial, and that our systems of classification attempt to draw a 

 hard-and-fast line where Nature has drawn none, or only a few here and 

 there. 



Looked at from one point of view. Nature may, however, be said to have 

 drawn some very hard-and-fast lines. If it were possible to examine every 

 species of bird which exists or has existed, we might find that all birds 

 were descended from one commoii ancestral species, and that, consequently, 

 every species of bird was connected with its nearest allies by an unbroken 

 series of intermediate forms ; in which case we should be obliged to admit 

 that there was only one species of bird, divisible into an immense number 

 of subspecies. Or we might find that birds are descended from several 

 ancestral bird-reptiles (so to speak), and that consequently there were 

 several species of birds, each divisible into an immense number of sub- 

 species. We have, however, only to deal in our classification with existing 

 species; and we at once perceive that by the extinction of species and 

 genera, to say nothing of families and orders. Nature has drawn some very 

 hard-and-fast lines, sometimes only narrow lines, but in many cases very 

 broad ones. 



When we come to deal with genera, the artificial character of our 

 classification at once reveals itself. The old-fashioned notion that species 

 were separated by differences of colour, and genera by structural differences 

 (that is, difference in the shape of the bill, feet, wings, or tail), is a pre- 

 Darwinian ornithological superstition, which is pure theory, and is entirely 

 unsupported by facts. There is no evidence of any kind that the leopard 

 can change his spots in a shorter time than it takes him to change the 

 shape of his skull. On the other hand, there is strong evidence to prove 

 that in many genera of birds colour or pattern of colour is more constant 

 than many of the so-called structural characters. The principal causes of 

 the chano-e of colour in birds are supposed to be to ensure protection from 

 enemies and to please the taste of the females, whilst the changes in the 



