brownish-white at the tip—the inner webs mostly white; the terminal half with just discernible obscure bars of darker, these becoming gradually obsolete on the basal half; sometimes they are entirely obsolete for the full length of the outer webs. Upper tail-coverts pure white, usually immaculate, but sometimes barred; inner webs of primaries ashy, the two or three outer ones more whitish, and sometimes barred with dusky. In males, the middle of the breast, the tibiæ, and crissum are usually ochraceous, irregularly spotted with brownish-black.
The darker-colored individuals in this stage are distinguishable from the dark examples of the young of B. swainsoni only by the very much stouter and longer tarsi.
The adults vary but little. The white of the jugulum usually reaches forward medially into the plumbeous of the throat, and in one (♂ ad., Tehuantepec, Mexico; Sumichrast) it extends—interruptedly, however—to the chin. Another male from the same locality has the scapulars almost entirely rufous, with black shaft-streaks. The white of the lower parts in the adult is of a pureness and continuity strikingly characteristic of this species.
A very young specimen from Paraguay has the tail more brownish, more distinctly barred, and more ochraceous on the tip; the upper tail-coverts are ochraceous, marked with broad crescentic bars of blackish, and the upper parts generally are variegated with ochraceous.
The specimen collected by Dr. Merrill (No. 74,464) is an adult male in fine plumage. It agrees strictly with Mexican examples of corresponding sex and age. Dr. M. furnishes the following notes on this specimen:—"Length, 19.20; extent, 47.40; wing, 15.30; tail, 7.20. Feet and legs yellow; cere greenish yellow; tip of bill dark, basal half bluish green; iris brown."
Material examined.—United States National Museum, 13; Museum of the Academy of Natural Sciences of Philadelphia, 6; Museum of G. N. Lawrence, Esq., 1; other specimens,[1] 4. Total number of specimens examined, 24.
| Sex and age. | Wing. | Tail. | Culmen. | Tarsus. | Middle toe. | Specimens. |
| ♂ ad. | 16.30—16.70 | 7.50— 9.00 | .95—1.10 | 3.30—3.55 | 1.60—1.80 | 5 |
| ♂ juv. | 14.50—16.75 | 8.60— 8.75 | 1.02— .... | 3.30—3.60 | 1.55—1.65 | 3 |
| ♀ ad. | 17.75— .... | 8.25— .... | 1.00— .... | 3.60— .... | 1.75— .... | 1 |
| ♀ juv. | 17.00—17.75 | 8.40—10.30 | .95—1.05 | 3.30—3.70 | 1.60—1.80 | 3 |
This fine Hawk is a rather common resident on the extensive prairies near the coast, especially about the sand ridges that are covered with yucca and cactus. Its habits appear to be like those of the allied species of Prairie Hawks. On the 2d of May, 1878, 1 found two nests, each
- ↑ These are specimens collected on the Isthmus of Tehuantepec by Prof. F. Sumichrast, and not entered in the Register of the National Museum.
