266 NORTH AMERICAN BIRDS. 



angle of moiitli down to the jui;uluni, witli nearly the wJiole pectm-al area, 

 luibrokeu black, lea\ing the gular region and side of the head pale, but 

 thickly streaked. "Wing, 15.00; tail, 8.80; tar-sus, 2.35; middle toe, 1.50. 

 These specimens may be said to ibrin about the extremes of the young plu- 

 mage. An Iowa skin (No. 59,052 ; Kicksecker) is like the average of far- 

 western examples. 



The melanistic condition bears to the normal [duniage of sioainsoni pre- 

 cisely the same relation that the black calurus, Cassin, does to the usual 

 style of the western variety of borcalis (borcalis var. calurus = montanus, 

 (^rssin) ; the variable series, connecting these two extremes, and designated 

 by the name horca/is var. calurus, which covers tlie whole, finds an exact 

 parallel in the present species. 



A specimen from the Platte (5,570, c? , August; W. S. Wood) is entirely 

 dark rufous-brown beneath (excepting the lower tail-coverts), with the shafts 

 of the feathers black. 



This species is entirely distinct specifically from the B. vulgaris oi Europe. 

 Tlie latter has four, instead of only three, outer primaries deeply emarginated, 

 and is very dissimilar in every stage of plumage. 



Var. uxyptei'us, Cassin. 

 SHAKP-WINGED HAWK. 



{Xonna! ijounr/ pliiiaaife.) 



Butco oxtjptcncs, C.\s.>^. P. X. N. S. VII, 185.5, 282. — Ib. Birds N. Am. 1858, 30.— 

 Stkickl. Oin. Syn. 1, 18.55, 28. — CouEs, P. A. N. S. 1866, 9. — Ge.\y, Hand List, 

 I, 8. — Cooper, Birds Cal. 1870, 480. Butco albicaudatus, "Vieill.," Sclater, P. Z. S. 

 1869, 634, No. 22. 



{Melanistic plumage. ) 

 Bufrn fiiliqim.ius, ScL.iTER, P. Z. S. I-ond. 1858, 356. — In. Trans. Z. S., .July, 1858, 267, 

 pi. l.xii. — KiDow.vY, P. A. N. S. Dec. 1870, 142. 



Sp. Cii.\r. Adult : melanistic plumage (Xo. 12,117, Mazatlan. Moxico; Colonel Abert). 

 Entirely fiiliginous-blaek, darkest on head and l)ack ; no white on forehead. Tail cine- 

 reous-umber, cro.'j.sed with .seven very regular and continuous bands of black, the subter- 

 minal one of which is broadest. Lower tail-coverts, and larger under wing-coverts, with 

 transverse bands of dull white ; lining of the wing unvaried black ; under surface of pri- 

 maries silvery-white, that portioti beyond their en:iargination black, the whitish portion 

 crossed by distant, very obsolete, transverse bars. Third quill longest; fourth and fifth 

 scarcely shorter, and nearly equal ; second equal to sixth ; first shorter than eighth. Tail 

 square; ,scutella3 of the tarsus very faintly defined, or, in fact, scarcely detectable (proba- 

 bly acoidental). Wing, 13.00; tail, 7.00; tarsus, 1.95; middle toe, 1.55. 



Young male ; normal plumage (No. 8,550, Fort Fillmore, New Mexico ; Dr. T. C. 

 Henry, U. S. A.). Head, neck, and lower part*, soiled ochraceous-white. Feathers of 

 the head above, and neck laterally and behind, with medial stripes of l)lackish-brown ; 

 juguluni, breast, sides, flanks, and abdomen, with large rounded spots of blackish-brown; 

 tiliiie with transverse liars of the same ; lower tail-coverts almost immaculate. A con- 

 spicuous " mustache " of blended dusky streaks, from angle of the mouth across the cheeks, 



