In regard to the form indicated in the above descriptions as “var. _striatulus_, Ridgway,” I am as yet undecided whether to recognize it as a geographical race, or to merely consider the two adult plumages as representing different ages of the same form. Certain it is that there is a decided difference in the young plumage, between the birds of this species from the eastern portion of North America and those from the western regions; these differences consisting in the very much darker colors of the western individuals, as shown by the above descriptions. My first impression in regard to the adult dress, after making the first critical examination of the series at my command, was, that the coarsely mottled specimens were confined to the east, and that those finely mottled beneath were peculiar to the west; and this view I am not yet prepared to yield. I have never seen an adult bird from any western locality which agrees with the eastern ones described above; all partake of the same characters as those described, in being finely and faintly mottled beneath, with sharp black shaft-streaks, producing the effect of a nearly uniform bluish ground, the black streaks in conspicuous contrast, the tail-bands nearly obsolete, etc. But occasional, not to say frequent, individuals obtained in the eastern States, which agree in these respects with the western style, rather disfavor the view that these differences are regional, unless we consider that these troublesome individuals, being, of course, winter migrants, have strayed eastward from the countries where they were bred. The Colorado female described above exhibits a rather suspicious feature in having a single feather, on the lower parts, which is coarsely barred, as in the eastern style, while all the rest are finely waved and marbled as in the western. If this would suggest that the differences supposed to be climatic or geographical are in reality only dependent on age, it would also indicate that the finely mottled individuals are the older ones. If future investigations should substantiate this suggestion as to the existence of an eastern and a western race of Goshawk in North America, they would be distinguished by the following characters:— Var. =atricapillus=. _Adult._ Markings of the lower surface coarse and ragged; feathers of the pectoral region with broad medial longitudinal streaks of the same slaty tint as the transverse bars, and with only the shafts black. Tail-bands distinct. _Young._ Pale ochraceous markings prevailing in extent over the darker (clear grayish-umber) spotting. Stripes beneath narrow, clear brownish; those on the flanks linear. Wing, 12.25–14.25; tail, 10.00–12.75; culmen, .80–1.00; tarsus, 2.90–3.15; middle toe, 1.70–1.95. _Hab._ Eastern region of North America.