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



EMPIDONAX FLAVIVENTRIS, B a i r d . 



Yellow-bellied Flycatcher. 



Tyrannulajlaviventris, Wm. M. and S. F. Baird, Pr. Ac. Nat. Sc.Phila. I, July, 1843, 283— Ib. Am. Journ. Science, 



April, 1844.— Audubon, Birds Amer. VII, 1844, 341 ; pi 490. 

 Tyrannulapusilla, (Swainson) Reimhardt, Vidensk. Meddel. for 1853 1854,82. — GLOCER,|Cab. Jour. 1854, 426. 

 Empidonax hypoxanthus, Baird, '(Provisional name for eastern specimens.) 

 Empiilonax dijficilisy Baird, (Provisional name for western.) 



Sp. Ch. — Second, third, and fourth quills nearly equal ; first intermediate between fifch and sixth. Tail nearly even, slightly 

 rounded. Tarsi long. Above bright olive green ; (very similar to the back of Ftreo novehoracensis ;) crown rather darker. 

 A broad yellow ring round the eye The sides of the head, neck, breast and body, and a band across the breast like the back, 

 but lighter ; the rest of the lower parts bright sulphur yellow ; no wlilte or ashy anywhere on the body. Quills dark brown ; 

 two bands on the wing formed by the tips of the primary and secondary coverts, the outer edge of the first primary and of the 

 secondaries and tertials pale yellow, or greenish yellow. The tail feathers brown, with the e.\terior edges like the back. The 

 bill dark brown above, yellow beneath. The feet black. In the autumn the colors are purer, the yellow is deeper, and the 

 markings on the wings of an ochry tint. Length, 5.15 inches ; wing, 2.83 ; tail, 2.45. 



JIab. — Eastern United States generally. Probably replaced on the Pacific by a closely allied species. 



This species is thick set in form ; the wings long, reaching as far as the middle of the tail, 

 or to the end of the upper coverts. The relative proportions of the second, third, and fourth 

 quills vary somewhat ; the third is, however, mostly a little the longest. The first is generally 

 a very little longer than the sixth ; considerably shorter than the fifth ; it is about .40 shorter 

 than the longest, which exceeds the secondaries by about .65 of an inch. The tail featliers are 

 rather narrow, and ratlier acute ; the lateral ones a little shortest. The bill is rather broad. 



This species is about the size of U. minimus, though rather stouter. The bill is broader ; 

 the colors are different, minimus not having the bright olive green of tbe back and yellow of 

 the under parts, even on the throat, which instead is whitish. In respect to color, flaviventris 

 differs materially from all our North American species. 



This species differs from some North American flycatchers in not having the uppermost tarsal 

 scutellae to envelope the outside of the bone, but reach only half way round, where the edge of 

 another series is seen opposite the first. The lower scales, however, follow the usual rule. 

 There is no naked space on the inner face of the tarsus. 



Although the specimens from the west coast are not sufficiently perfect to allow of a full 

 criticism, I am inclined to think that they are really distinct, and' that they will not constitute 

 almost the single exception to the fact that no flycatcher is common to both east and west 

 coasts. The colors are lighter, and duller ; the olive more yellowish, and the bands and 

 edges of the wings narrower and less distinct. The forehead has a peculiar hoary appearance. 

 The first quill is intermediate between the sixth and seventh, and half an inch less than the 

 longest ; the second considerably shorter than the fourth. . In Jlavivenlris the first is rather 

 longer than the sixth ; the second and fourth equal. In view of all these circumstances, there- 

 fore, it may be well to give it provisionally a new name, and none would be more appropriate 

 than that of Empidonax difficilis. 



Tlie Muscicapa flaviventris of Vieillot (Ois. Am. Sept. I, 1807, 70) is clearly distinct in the 

 larger size, rufous tinge above, absence of yellowish on the throat and breast, etc. Wliat the 

 species really is is not well ascertained, nor whether it actually belongs to tliis group. It is 

 spoken of as inhabiting St. Domingo. Should it prove to be of the same genus the present 

 species may be called hypoxanthus in allusion to the yellow of the under parts. 



