characters are correlated with them, such as the possession or not of a 

 special apparatus for singing, and the existence or not of one common 

 carotid artery or of two, besides numerous peculiarities of muscles and 

 of bones. 



When more minute subdivisions can no longer thus be made, 

 certain well-defined types have to be chosen ; and all the birds with 

 the clearest affinities to these are grouped about them. Thus the first 

 or greater division of the Oscines comprises some five more or less 

 well-marked types among British birds : warblers and thrushes 

 characterize one "cohort;" finches and buntings, another; crows, a 

 third; creepers, a fourth; swallows, a fifth. Of course. each cohort 

 contains forms more or less divergent from the type, but in every case 

 such apparent anomalies bear closer relationships to the type associated 

 with each than to the type of any other. 



In a similar way the birds with independent young Dasypaedes 

 fall into four orders, viz., birds of prey, fowl-like birds, waders, and 

 swimming birds. In the first order, Accipitres, most have the head 

 feathered, and these seek their prey either by night, as owls, or by 

 day, as hawks and eagles ; while others, the vultures, have the head 

 bare. 



Thus group after group is treated, and so the affinity of one species 

 or genus to another is shown in a far clearer way than any simply 

 linear arrangement could possibly effect ; just as, to use an illustration 

 employed by the late J. S. Mill, all towns could be arranged according 

 to their respective distances from the poles, but it is much more con- 

 venient to regard them as situated in such and such a continent or 

 country. 



But, it may be asked, since in such a series of groups one must be 

 placed first and another last, how is it to be determined which has the 

 claim to the higher place and which to the lower ? Of the two primary 

 divisions, that which undergoes the greatest variety of changes subse- 

 quent to birth seems naturally to take precedence in the all-important 

 matter of development. Hence the orders Oscines and Volucres come 

 to head the list, and of these the Oscines are regarded as the higher 

 type, because among them occur the most highly specialised of birds ; 

 while in the other great division the birds of prey have the priority, 

 partly by reason of the nearer accord of their nesting habits to those 

 of the higher class, partly by reason of their great specialisation ; and 

 the swimmers are placed last, because they include some of the 

 simplest of birds. Every animal is necessarily more or less fully 

 adapted to its environment ; but it is clear that, in the struggle for 

 life, a nightingale must needs be prepared for an infinitely more varied 

 range of circumstances than a petrel or a penguin. 



HENEY T. WHABTON. 



