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U. S. p. R. R EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



the tail feathers are narrow linear to near the end, where they are slightly spatulate, while in 

 M. tyrannus they are hroader at the base, and taper gently to the end. The legs of M. forficatus 

 are larger, and the linear attenuation of the primaries confined to the first one, extending over 

 an inch. 



In 31. tyrannus the outer three primaries share a linear attenuation, but this does not amount 

 to half an inch in length. The colors are very different, 31. forficatus being whitish ash above, 

 the rump black, the tail feathers rose white with black at the tips, the shoulders and belly light 

 vermilion. 31. tyrannus, on the other hand, has a black head and tail, the outer edge of the 

 latter only white, the back olivaceous, the under parts pure white. The two species differ in 

 some points of structure, and are separated generically by some authors. 



Comparative measurements of species. 



MILVULUS TYRANNUS, Bon. 



9 Fork-tailed Flycatcher. 



Muscicapa tyrannus, Linn. Syst. Nat. I, 1766, 325. 



Milvulus tyrannus, Eonap. Geog. Li.-st, 1838. — Audubon, Synopsis, 1839, 38. — Ib. Birds Atu. I, 1840, 196 : pL 52. 



Despotes tyrannus, Bonap, Comptes Rendus, 1854, 87. 



Tyrannus savana, Vieillot, Ois. Am. Sept. I, 1807, 72 ; pi. xliii. — Swainson, Mon. Ty. Shrikes ; Quarterly Jour. 



XX, Jan. 1826, 282. 

 Muscicapa savana, Bonaparte, Amer. Orn. I, 1825, 1 ; pi. i, f. 1. — Audubon, Cm. Biog. II, 1834, 387 ; pi. 168. 

 Milvulus savanus. Gray, List, 1841. 



? Tyrannus viokntus, Vieill. Encyc. Metli. II, 853- — Burmeister, Thiere Brasiliens, Vogel, 1856, 467. 

 ? Tyi-annus nunciola, Stephens, Shaw Gen. Zool, Birds XIII, ii, 1826, 133. 

 Tyrannus milvulus, Nuttall, Man. 2d ed. I, 1840, 307. 

 Fork-tailed flycatcher. Pennant, Latham. 

 Tyran a queue fourchue, Buffon, pi. enl. 571. 



gp. Ch. Outer four primaries abruptly attenuated at the end, the sides of the attenuated portion parallel. Second and third 



quills longest ; fourth little shorter, and not much exceeding the first. Tail very deeply forked ; the external feather linear, 

 and twice as long as the head and body alone. Top and sides of the head glossy black. Rump, upper tail coverts, and tail 

 almost black ; the outer web of outer tail feather yellowish white for more than the basal half; rest of upper parts ash gray. 

 Under parts generally pure white. Wings dark brown ; the outer primary and tertials edged with white. Crown with a con- 

 cealed patch of yellow. Length 14 inches ; wing 4.75 ; tail 10 inches ; depth of fork 7 inches. 



Hab. — South America. Accidental in the United States. 



This species claims a place in the fauna of the United States on account of two specimens 

 captured in New Jersey, at long intervals, and one or two seen by Mr. Audubon in the south- 

 west. 



List of specimens. 



