Falco fuscus, and dubius, Gmel. and Lath.
Slate-coloured Hawk, Falco Pennsylvanicus, Wils. Amer. Ornith. vol. vi. p. 13, pl. 46, fig. 1. Adult Male.
Sharp-shinned Hawk, Falco velox, Wils. Amer. Ornith. vol. vi. p. 116, pl. 45, fig. 1. Young Female.
Falco velox, Ch. Bonaparte, Synopsis of Birds of United States, p. 29.
Falco fuscus, Ch. Bonaparte, Ibid. Append. p. 433.
Accipiter Pennsylvanicus, Slate-coloured Hawk, Richards. and Swains. Fauna Bor.-Amer. vol. ii. p. 44.
American Brown or Slate-coloured Hawk, Nuttall, Manual, vol. ii. p. 87.
Adult Male. Plate CCCLXXIV. Fig. 1.
Bill short, with the dorsal line of the upper mandible curved from the base, so as to form nearly the fourth of a circle, the sides sloping rapidly and convex toward the end, the edges sharp anteriorly, with a broad tooth-like process or prominent festoon about the middle, the tip very acute and decurvate; the cere rather short, its margin forming a convex curve before the nostrils, which are oblique, oblongo-ovate, broader behind; the lower mandible with the angle broad and short, the dorsal line convex, the back broad at the base, the sides convex, the edges inflected, the tip obliquely truncate, rounded, with a very faint sinus behind.