108 



greatest * variety of color, it seems to me more reasonable to adopt 

 the last conclusion. 



On carefully examining a large series of specimens, principally in 

 the collections of the Smithsonian Institution at Washington, and of 

 the Academy of Natural Sciences at Philadelphia, I find that all of 

 them belonging to Harlani ?, insignatus, Swainsonii, Bairdii, oxypterus, 

 borealis, montanus, calurus, and perhaps Cooperi, can be easily re- 

 duced to two very distinct groups, each of which is distinguishable by 

 definite external characters, and in which the variations of plumage, 

 though apparently so great, if the extremes only are taken into con- 

 sideration, can, it seems to me, be arranged in a series, in which the 

 connection of the different members may be readily traced. Of these 

 two groups or rather species, one, which should be called B. borealis, 

 as the first described, consists of that species, montanus, calurus, 

 f Harlani ? and probably Cooperi, and is characterized by a very 

 muscular body, stronger and larger bill, longer and more powerful 

 tarsi, and a more rounded wing, the fourth quill generally the longest, 

 the fifth little, if any, shorter than the third, and the first always 

 shorter than the eighth. The other species, to which Harlani ?, in- 

 signatus, Swainsonii, Bairdii, and oxypterus belong, is distinguished 

 by a more slender body, shorter and weaker tarsi, and a more pointed 

 wing, the third quill generally the longest, the fifth considerably 

 shorter than the third, and the first always longer than the eighth. 

 It is a matter of some doubt what name should be assigned to this 

 species. I have seen specimens which agree very exactly with Audu- 

 bon's plate of B. Harlani, and if they are really specimens of his 

 bird, that name would have priority. Though his type specimen in 

 the British Museum is said, by some of the English ornithologists, to 

 belong to the other species, I am inclined to doubt this, as there is 

 a specimen of B. fuliginosus in the collection of the Academy, marked 

 B. Harlani, by Audubon himself, and it is almost impossible for him 

 to have mistaken this bird for a red-tailed hawk. I shall, therefore, 

 at present consider this species to be B. Harlani. If the type in the 

 British Museum should prove to be a different bird, Sicainsonii, as 

 next in date, would take its place. 



On making the examinations which led to the conclusions above 

 stated, I was struck by the small number of specimens in which all 

 the feathers were equally developed; and when they were so, the 



* "In the coloring of the feathers of this bird tliere prevails a most extraordi- 

 nary difference, and one which is not often seen in other birds of prey. From the 

 darkest, uniform, blackisli-brown to the purest white, we find all the shades, and 

 also both colors mixed and spotted, in such various ways, that tlie countless transi- 

 tions ciiiiiiot be (lescrihod ; this difference is independent of age and sex." Nau- 

 mann''s Nat. Hist, of the Birds of Gerynany, vol. i. p. o47. 



t There is a .specimen marked Harlani in the collection of the Academy, which 1 

 consider to beloi);j; to tliLs groiii). 



