MUSEUM OF COMPARATIVE ZOOLOGY. 335 



has observed, is " a character quite unusual in any rapacious bird," * though 

 I do not see that in this respect it differs essentially from Buteo linealus, 

 B. pennsylcanicus, or Circus cj/aneus, etc. Its other main point of differ- 

 ence from the H. leucocephalus is its greater size. Audubon described 

 his bird as measuring " 3 feet 7 inches in length," "10 feet 2 inches " in 

 extent of wings, and the folded wing "32 inches." In this series of 

 measurements there is no discrepancy between the different dimensions 

 given — the proportions being exactly the same as in H. leucocephalus — 

 that might lead to the suspicion of a typographical or other accidental er- 

 ror, as some writers, have suggested there maybe in respect to the alar 

 extent. It is, then, either a valid species or a large individual of //. leu- 

 cocephalus, or a large immature H. albicilla. Since known specimens of 

 H. leucocephalus sometimes nearly approach the supposed //. Washing' 

 toni in size, it seems not unreasonable, on the whole, to regard it as 

 reallv a remarkably large example of //. leucocephalus in immature 

 plumage. Audubon describes his bird as breeding within the United 

 States, and hence it is hardly probable it coidd have been the arctic 

 H. albicilla, which has never, so far as known to me, been observed 

 60 far south at any season of the year. In reference to its fishing habits, 

 supposed by Audubon to distinctively characterize it, it is now well known 

 that the //. leucocephalus will occasionally capture its own fish, instead of 

 depending wholly upon robbing the fish-hawk for them. 



Mr. Cassin further observes, f respecting the H. Washingioni, that he 

 believes it to be more nearly related to his //. pelagica, which he describes 

 as " the largest of eagles," than to any other. In the same connection he 

 judiciously remarks respecting the numerous apocryphal species of eagles 

 on record as follows : " But there is no end to the accounts of strange 

 eagles given by travellers and naturalists. Some of them may have refer- 

 ence to peculiar species which have in later times escaped attention, but 

 the probability is they more frequently allude to accidental varieties, or 

 that the authors describe from such reports as they had heard at second 

 hand, or fell into error from insufficient personal observation." Many of 

 these reports he alludes to in detail, including the reference by Captain 

 Cook % to a " black eagle " with a " white breast " seen by.him at Kay's 

 Island, on the northwest coast of America. A specimen of the //. leu- 

 cocephalus in peculiar (probably albinic) plumage in the Museum of Com- 

 parative Zoology, taken in Eastern Massachusetts, seems to indicate that 

 the eagle of Captain Cook may have been but an unusual stage of colora- 

 tion of the common white-hea'ed eagle. The Massachusetts specimen 



* Baird's Birds of X. America, p. 42. 

 t Illust. Birds of Cal. and Texas, p. 36. 

 *J Cook's Voyages, II, 352, 1784. 



