Of the several new species of rapacious birds of North America, which have been discovered within a few years, the bird now before the reader is one of the most interesting. It is the second species now ascertained to inhabit this continent, of a group constituting the typical genus _Buteo_ of naturalists, which until a recent period was supposed to be peculiar to the Old World, the previously known American species being Swainson’s Buzzard (_Buteo Swainsonii_), a bird of the northern regions, little known and nearly lost sight of until recently by ornithologists. The birds of this group are more active and Falcon-like in their habits than the other species of the North American Buzzards, all of which have been classified in other sub-genera. They also appear to be more strictly predatory in their habits. The present species was discovered by P. R. Hoy, M. D., an active and enthusiastic naturalist of Racine, Wisconsin, who first observed it and obtained specimens in the vicinity of that city. In the same State, it has also been observed by the Rev. A. O. Barry, of Racine, and Mr. William Dudley, of Madison, both naturalists of extensive acquirements, who have done much to elucidate the zoology of that district. All of those gentlemen concur, however, in representing it as very probably a visitor only in Wisconsin, and migrating to more northern regions of the continent of America. In addition to their specimens, we have seen one other only, which is contained in a collection now deposited in the National Museum, Washington, and was obtained near the Great Salt Lake, Utah Territory, by Lieut. E. G. Beckwith, of the United States Army, in whose charge a party surveyed one of the proposed routes for a Railroad to the Pacific Ocean. We have to express our obligations to Dr. Hoy for his kindness in furnishing the following notice of this bird for our present article:— “Although never numerous, this fine Hawk is not unfrequently met with during the fall and spring, especially in the vicinity of Racine, but is exceedingly wary and difficult to approach, and as it is here an inhabitant almost exclusively of the prairies, the procuring of specimens even by an experienced hunter or collector, is almost entirely dependant on encountering it accidentally within gunshot. “This bird may be readily known, though seen at a considerable distance or heighth in the air, by its long pointed wings and rapid flight; in the last respect somewhat resembling the Duck Hawk (_Falco anatum_), and in fact looking somewhat like that species when on the wing. I witnessed not long since, a bird of this species flying rapidly, but he wheeled about suddenly and struck into a covey of Partridges with wonderful celerity of movement, and bore off in his talons sufficient evidence that his exploit had been fully successful. This bird possesses much greater activity of habits than any other of our Hawks of the same genus (_Buteo_), and its mode of flight is quite different.