HABITS. Only two specimens of this Hawk have been taken within the limits of the United States. One was obtained by Dr. Heermann on the vast plains of New Mexico, near the United States boundary-line. It appeared to be flying over the prairies in search of small birds and mice, at times hovering in the manner of the common Sparrow Hawk (_Tinnunculus sparverius_). It appears to be resident throughout a large part of Mexico, and in Central and South America. The other is from the Rio Pecos of Texas, collected by Dr. W. W. Anderson. Mr. Darwin, in his Zoölogy of the Voyage of the Beagle, mentions obtaining one specimen in a small valley on the plains of Patagonia, at Port Desire, in latitude 47° 44′ south. M. D’Orbigny supposed latitude 34° to be the extreme southern limit of the species. Lieutenant Gilliss brought specimens from Chile. Mr. Darwin states that the _F. femoralis_ nests in low bushes, this corresponding with the observations of Mr. Bishop. He found the female sitting on her eggs in the beginning of January. According to M. D’Orbigny, it prefers a dry, open country with scattered bushes, which Mr. Darwin confirms. Mr. Bishop informs me that he met with this Hawk in the greatest abundance upon those vast plains of South America known as the Pampas, in which no trees except the ombû are found, and that it there nests exclusively on the tops of low bushes, hardly more than a foot or two from the ground. The bird was not at all shy, like most Hawks, but was easily approached so nearly as to be readily recognized. Mr. Bridges states, in the Proceedings of the London Zoölogical Society (1843, p. 109), that the _H. femoralis_ is trained in some parts of South America for the pursuit of smaller gallinaceous birds, and that it is highly esteemed by the Chilian falconers. It very soon becomes quite docile, and will even follow its master within a few weeks of its capture. I am indebted to Mr. N. H. Bishop for specimens of the eggs of this Hawk obtained by him on the Pampas. The nest contained but two, and was built on the top of a low bush or stunted tree, hardly two feet from the ground. It was constructed, with some pains and elaboration, of withered grasses and dry leaves.