NATURAL SCIENCES OF PHILADELPHIA. 109 



able one in every way, and is entirely aberrant and exceptional in 

 its peculiar features. The relative position of the areas where light 

 and dark markings respectively prevail is exactly reversed, the pec- 

 toral region being white, with a longitudinal tear-shaped spot of 

 blackish-brown on the tip of each feather, while the abdomen, sides, 

 and flanks are so heavily marked with more or less confluent trans- 

 verse spots and bars of dark brown, that this forms the predomi- 

 nant color of those parts; the tibiae are finely and regularly barred 

 with dark brown. The style of coloration of the lower parts of 

 this specimen strikingly calls to mind that of the adult, normally 

 colored Archibuteo lagopus (vax.sancti-johannis). The gular region 

 is white, with a conspicuous medial stripe of dark brown, while it 

 is bordered on either side by a broader one of the same color. The 

 ear-coverts are so much streaked with white that this color pre- 

 vails ; while the neck is very heavily spotted with the same at the 

 bases of the feathers. The measurements are as follows: wing, 

 16.70 ; tail, 9.00; culmen, .95; tarsus, 2.90; middle toe, 1.65. 

 This specimen was obtained May 29, 1868, on the Wahsatch 

 Mountains, Utah, by Mr. L. E. Ricksecker. The sex is queried 

 as male upon the original label. Altogether, it is so far out of 

 the usual range of variation which obtains in the species, that it 

 may possibly eventually prove to belong to another species. 



The melanistic plumage grades from individuals only a little 

 darker beneath (with less-defined bars) than the clearly-barred ones 

 described above, up to others which are entirely black, except the 

 crissum and tail. The latter is always as in the normal plumage, 

 while the former always has some white this forming the pre- 

 vailing color in seven out of eight examples. Of the eight speci- 

 mens before me, only two have the crissum immaculate white, and 

 have much white on the throat. One of them has the tibiae and 

 anal-region narrowly barred with light rusty. Three others have 

 the white of the crissum marked with a very few, distant, and 

 faint bars of rusty. Two others are broadly barred with blackish- 

 brown, while the remaining one (No. 12,117, Mazatlan, Western 

 Mexico) has these black bars so much wider than the white ones 

 that the crissum seems black barred with white, rather than the 

 reverse. Two specimens (No. 12,117, Mazatlan, and No. 22,569, 

 Onion River, Arctic America) are absoluteby uniform and continu- 

 ous brownish-black, except the crissum. No. 6,455, Nebraska, has 

 the breast and tibiae bright rufous, the lining of the wing rusty 



