44 PROCEEDINGS OF THE ACADEMY OF 



B. Swainsoni, Bonaparte, Conspectus, i. p. 19. Cassin, Birds Cal. and 



Tex. i. p. 98 (1853) ; but not of Cassin, B. N. A. (1858). 

 Falco buleo, Audubon, Orn. Biog. ; Sw. & Rich. F. B. A., according to 

 Cassin. 



The most abundant and characteristic species of the larger Hawks; resi- 

 dent, but particularly abundant during the winter months. It may be 

 readily recognized at any distance, when flying, by the very dark-colored 

 area presented by the lesser under wing coverts, sharply contrasted against 

 the very light colors of the rest of the under surface of the wings. The iris 

 is clear light brown ; the bill bluish black ; the cere, legs and feet light 

 yellow. 



In the Proceedings of the Boston Society of Natural History for 1861, 

 appeared a paper by Dr. Henry Bryant, on the variations of the plumage of 

 Western North American Buleones ; in which facts are elicited tending to 

 demonstrate that nearly all the species enumerated as valid by Mr. Cassin, in 

 1858, may be reduced to two. One of these, of which borealis Gm may be 

 taken as the type or parent stock, and for which the name must stand, is 

 large and muscular, with a strong bill, long stout tarsi, and a rounded 

 wing. Here Dr. Bryant would range montanus Nutt., calurus Cass., and pro- 

 bably also Cooperi Cass. ; together with a specimen in the Philadelphia 

 Museum, which has been labelled and usually called Ifarlani. The other 

 species is distinguished by its smaller size, more slender form, longer and 

 weaker tarsi, and more pointed wing. Harlani* Aud. is considered as the 

 first name of this species ; and to it are referred Swainsonii,f Bairdii of Hoy % 

 and of Cassin; insignatm,?^ Cassin, and oxypterus || Cassin. Dr. Bryant gives 

 careful measurements of these supposed species, having access to the types 

 of many of them, and fiuds that, if we are to take size and proportions 

 alone as indicative of specific validity, we can admit but the two species he 

 characterizes ; while, if we are to be guided by color, we cannot avoid still 

 further increasing the number of species to be recognized to such an extent, 

 that (together with the other undoubted species, such as linea/as, pennsyl- 

 vanicus, etc.,) we should have a total of twenty- three inhabiting North 

 America. 



It cannot be denied that our constantly increasing knowledge of the dis- 

 tribution of North American Buteones, and of the "theory of variation" 

 which is applicable to them, decidedly tends towards a confirmation of Dr. 

 Bryant's views. Nevertheless, I am by no means prepared to accept with- 

 out reservation the extreme conclusions arrived at. I prefer, at present, to 

 enumerate the species or varieties, if they are only such as determined by 

 Mr. Cassin ; considering the names given as at least indicative of strongly 

 marked, and apparently geographical, though perhaps not permanent, 

 varieties. 



11. Buteo "calurus" Cassin. 



B. calurus, Cassin, Pr. A. N. S. Ph. 1855, p. 281 ; and B. N. A. 1858, p. 22. 



" B. borealis Gm." Bryant, 1. c. 

 Resident at Fort Whipple, and by no means rare. Specimens taken in the 

 winter of 18645, and in April following. Orig. No. 1246; $. Length 

 23'75; extent 55'50. Iris light yellow. Bill dusky bluish horn. Cere dull 

 yellowish green. Mouth livid flesh color. Legs and feet chrome yellow. 

 Claws black. 



*"Harlani Aud.," of which the type is in the British Museum, is given by Cray (Cat. Brit. 

 Mus. Accipitres) as borealis. If such be the truth, that Audubon's species was founded upon the 

 fuliginous state of plumage of borealis, then Swainsoni Bp. is the first distinctive name of the 

 smaller of the two species recognized by Dr. Bryant. 



+ 0f Bonaparte, Comp. List, 1838, p. 3, as defined by Cassin, B. N. A., 1858, p. 19. 



IB. Bairdii, Hoy, Pr. A. N. S. Ph. vi. 1853, p. 451. Cassin, B. of Cal. and Tex. pi. 41. Idem, B. 

 N. A., 1858, p. 21. 



$ B. insignatus, Cass., B. of Cal. and Tex., 1854, p. 102, pi. 31. B. N. A., 1858, p. 23. 



11 B. oxypterus, Cass., Pr. A. N. S. Ph. vii. p. 282 Id. B. N. A., 1858, p. 30. 



[Ma-ch, 



