308 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



or mikado brown, and with the bars below with a rufescent cast and 

 sometimes confluent on the breast to the near exclusion of the white. 



Adult. — AIelanistic phase (sexes alike): Plumage of head, neck, 

 and body, entirely continuous dark sooty brown, without the faintest 

 indication of markings, even on the lower tail coverts or lining of the 

 wing; back darker, with a chalky cast in certain lights. Wing similar 

 to the general plumage, but somewhat lighter brown, on account of 

 paler but not well-defined borders to the feathers; secondaries lighter 

 b^o^^^l than the coverts, without trace of markings except near the 

 end, where crossed by a broad dusky subtcrminal band and very 

 narrow paler terminal margin; primaries uniform dusky brown on 

 outer webs, growing gradually blackish terminally; inner webs of the 

 three outer quills chiefly white anterior to their emargination (the 

 portion near the shaft brownish), the white crossed by several very 

 distinct but irregular bands of blackish; inner webs of remaining pri- 

 maries, and also of secondaries, bro\^Ti, with a greater or less number 

 (according to the length of the feather) of dusky bands, the webs 

 mottled with whitish along the edge. Upper tail coverts with concealed 

 pale grayish broad bars (approaching white in places), there being 

 about two bars on each feather. Tail black, narrowly tipped with 

 grayish browai, crossed at about 36 mm. from the end by a broad 

 band (about 25 mm. wide) of brownish gray, becoming white on edges 

 of inner webs, and approaching white on the anterior portion of the 

 band on the middle rectrices; another much narrower and much less 

 distinct gull grayish band crosses the tail about 100 mm. from the tip, 

 the portion on inner webs more or less whitish on some of the feathers, 

 but on none extending clearly to the edge of the web; extreme base 

 of the tail light sooty grayish. Feathers of the head, neck, and body, 

 above and below, sooty gray beneath the surface, the extreme base 

 even scarcely approaching white; the feathers of the entire occiput, 

 however, abruptly snow-white for about the basal half. Forehead 

 entirely sooty blackish, but anterior portion of the lores grayish white, 

 finely streaked with black. "Iris red." 



The melanistic phase of this species is so rare that only a very 

 few specimens have hitherto been recorded. They resemble very 

 closely in size and general appearance the melanistic phase of Buteo 

 brachyurus Vieillot, from which they may be distinguished by the 

 middle toe which without the claw is shorter than the bare part of the 

 tarsus in front in B. platypterus and longer in B. brachyurus. 



Immature. — Normal phase (sexes alike): Similar to adults but 

 with the dark marks on the breast longitudinal streaks, not bars, the 

 broad median shaft stripes not or only slightly incised laterally by the 

 white margins of the feathers. This is a rather indefinite plumage and 



