190 Neiv and fori hcominy Ornithological Works, ^c. 



opinion that he has pushed matters too far, and that he, and the 

 writers he seeks to refute, represent, as it were, the opposite 

 limits of a pendulum's oscillation, the golden mean lying 

 between the two. A prominent case in point is that of the 

 Buzzards of North America. 



Mr. Allen states his present opinion to be, that (putting 

 B. lineatus aside) all the so-called species may be referred to 

 B. borealis and B. pennsylvanicus, to which B. oxypterus of Cassin 

 is united. We much doubt the possibility of maintaining the 

 number of species claimed by Baird and others ; but we cannot 

 refrain from putting in a plea for B. swainsoni, which, so far as 

 our experience goes, never assumes the red tail so characteristic 

 of jB, borealis. With B. swainsoni, B. insignatus must be placed ; 

 and it yet remains to be seen how far this bird differs from 

 B. vulgaris of the northern portion of the Old World. The true 

 B. harlani must, we think, be called a melanism of B. borealis. 

 As for B. oxypterus we have always considered B.fuliginosus of 

 Sclater synonymous with it ; and if so, it is not B. pennsylvanicus 

 as Mr. Allen asserts. Take another case : Scops maccalli is placed 

 as a synonym of S. asio ; the name really is synonymous with 

 S. trichopsis of Wagler, the bird being quite distinct from S. asio, 

 as has been pointed out elsewhere*. 



Some useful generalizations respecting the distribution of 

 North- American birds form the next portion of this instructive 

 paper; but here again Mr. Allen is led outside his immediate 

 subject into a sketch of his views of the distribution of ornithic 

 life on the globe's surface. Finally, we have a list of works on 

 American ornithology, classified according to the countries to 

 which they especially apply; but again we find, especially in 

 Central America, that the classification laid down has not been 

 very accurately adhered to. 



This memoir will, we believe, act as a useful antidote against 

 the undue tendency to recognize species; but we must repeat 

 our warning that too much stress should not be laid on the sup- 

 posed action of physical laws upon the plumage, bills, &c. of birds. 

 Then again these climatic variations require the closest attention, 

 and it is yet a question under which system they receive the 



* Cf. P. Z. S. 1868, p. 57. 



