_Adult female_ (12,927, Utah Valley, July; C. S. McCarthy). Similar; lower tail-coverts white, tinged with rusty, and barred with brown; tibiæ tinged with chestnut. Wing, 16.50; tail, 8.80; tarsus, 2.60; middle toe, 1.65. Third and fourth quills equal and longest; third shorter than fifth; first equal to eighth. LIST OF SPECIMENS EXAMINED. National Museum, 27; Philadelphia Academy, 2; Boston Society, 1; Museum, Cambridge, 1; Cab. G. N. Lawrence, 2; W. Brewster, 1; R. Ridgway, 5. Total, 39. _Measurements._ +----+-----------+-----------+---------+---------+-----------+----------+ |Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.|Specimens.| +----+-----------+-----------+---------+---------+-----------+----------+ | ♂ |14.40–15.25| 8.25–9.00| .80–.90|2.30–2.65| 1.50–1.60| 11 | +----+-----------+-----------+---------+---------+-----------+----------+ | ♀ |14.75–16.50| 9.00–0.00| .80–.95|2.50–2.70| 1.55–1.65| 11 | +----+-----------+-----------+---------+---------+-----------+----------+ HAB. Western regions of North America, east to the Mississippi Valley, north to the Arctic regions; Wisconsin; Arkansas; Canada; Massachusetts. Localities: S. Texas (DRESSER, Ibis, 1865, 324); Arizona (COUES?); Guatemala (SCL. Ibis, I, 216, “_insignatus_”). The young plumage described above is the _Buteo bairdi_, Hoy, of authors. The melanistic plumage is _B. insignatus_, Cassin. The young birds of this species are as variable as the adults; thus, No. 53,210, ♂, has the fine ochraceous of the lower parts entirely free from spots, except across the breast; on the upper parts the ochraceous spotting is so extended as to almost prevail, while another, from the same nest, has the black beneath exceeding the ochraceous, the tibiæ being thickly spotted, and the lower tail-coverts barred. Both these specimens belong to a brood of four, which were hardly able to fly, and were shot, with their parents, the male of which is the one described, while the female (No. 53,206) is a very dark example of _insignatus_, Cassin. The type of _bairdi_, and another Wisconsin specimen, are in the collection of the Philadelphia Academy. In plumage, they are unlike any others I have seen, though there is as little resemblance between these two as between any I have compared. Dr. Hoy’s type (Racine, Wisc., January, 1854) differs from others, in exceedingly pale colors; the cream-color beneath is scarcely spotted, there being only a few triangular spots and shaft-lines of black on the sides; the lining of the wing is entirely immaculate. Above, the black is unusually continuous; the under surface of the primaries is unusually white. Wing, 15.00; tail, 8.00.