_Accipiter cauda furcata_, CATESBY, Carolina, I, pl. iv, 1754. _Falco forficatus_, LINN. Syst. Nat. I, 89, 1758. _Falco furcatus_, LINN. Syst. Nat. p. 129, 1766.—PENN. Arct. Zoöl. p. 210, No. 108, pl. x.—GMEL. Syst. Nat. p. 262. _Nauclerus forficatus_, RIDGWAY, P. A. N. S. Phil. Dec. 1870, 144.—DAUD. Tr. Orn. II, 152.—SHAW, Nat. Misc. pl. cciv; Zoöl. VII, 107.—WILS. Am. Orn. pl. li, f. 3, 1808.—AUD. Birds Am. pl. 72, 1831; Orn. Biog. I, 368; V, 371.—BONAP. Ann. Lyc. N. Y. II, 31; Isis, 1832, 1138. _Milvus furcatus_, VIEILL. Ois. Am. Sept. pl. x, 1807. _Elanoides furcatus_, GRAY, List B. Brit. Mus. p. 44, 1844.—STRICKL. Orn. Syn. I, 141, 1855.—OWEN, Ibis, II, 1860, 240 (habits). _Nauclerus furcatus_, VIG. Zoöl. Journ. II, 387; Isis, 1830, p. 1043.—LESS. Man. Orn. I, 101; Tr. Orn. p. 73.—SWAINS. Classif. B. I, 312; II, 210, 1837.—BONAP. List, p. 4; Cat. Ucc. Eur. p. 20; Consp. Av. p. 21.—GOULD, B. Eur. pl. xxx.—AUD. Synop. p. 14, 1839.—RICH. Schomb. Reis. Brit. Guian. p. 735.—DE KAY, Zoöl. N. Y. II, p. 12, pl. vii, f. 15.—GRAY, Gen. B. fol. sp. 1, pl. ix, f. 9; Gen. & Subgen. Brit. Mus. p. 6.—BREW. (WILS.) Synop. Am. Orn. p. 685.—WOODH. Sitgr. Exp. Zuñi & Colorado, p. 60.—KAUP, Monog. Falconidæ, Cont. Orn. 1850, p. 57.—BREWER, Oölogy, I, 1857, 38.—CASS. Birds N. Am. 1858, 36.—COUES, Prod. Orn. Ariz. 1866, p. 12.—DRESSER, Ibis, 1865, 525 (Texas, nesting).—GRAY, Hand List, I, 27, 1869. _Elanus furcatus_, VIG. Zoöl. Journ. I, 340.—STEPH. Zoöl. XIII, pl. ii, p. 49.—CUV. Règ. An. (ed. 2), I, p. 334.—JAMES. (WILS.) Am. Orn. I, 75.—JARD. (WILS.) Am. Orn. II, 275.—JARD. Orn. Eur. p. 29.—NUTT. Man. p. 94. _Accipiter milvus carolinensis_, BRISS. Orn. I, 418, 1760. _Elanoides yetapa_, VIEILL. Enc. Méth. III, 1205, 1823. SP. CHAR. _Adult_, _male_ and _female_. Whole head and neck, lining of wings, broad band across the rump, and entire lower parts, pure white. Interscapulars and lesser wing-coverts, rich, dark, soft, bronzed purplish-black. Rest of upper parts, including lower part of rump, upper tail-coverts, and tail, more metallic slaty-black, feathers somewhat greenish basally, more bluish terminally, with a peculiar, soft milky appearance, and with very smooth compact surface. Tertials almost entirely white, black only at tips. White on under side of wing occupying all the coverts, and the basal half of the secondaries. Wing, 15.40–17.70; tail, 12.50–14.50; tarsus, 1.00–1.30; middle toe, 1.15–1.20. _Younger._ Similar, but with the beautiful soft purplish-bronzed black of shoulders and back less conspicuously different from the more metallic tints of other upper parts. _Young_ (youngest? 18,457, Cantonment Burgwyn, New Mexico). The black above less slaty, with a brownish cast, and with a quite decided gloss of bottle-green; secondaries, primary coverts, primaries, and tail-feathers finely margined terminally with white. Feathers of the head and neck with fine shaft-lines of black.