=633.1. Least Vireo= (_Vireo pusillus_). L. 4.8. _Ads._ Above gray, slightly tinged with greenish toward rump; below white, sides with little if any greenish tinge; one inconspicuous whitish wing-bar; lores and eye-ring inconspicuously grayish.
Range.--Northwestern Mexico and northern Lower California; breeds north to Arizona and middle California.
=634. Gray Vireo= (_Vireo vicinior_). L. 5.5. Above slaty gray; below white tinged with grayish; one inconspicuous wing-bar; lores and eye-ring gray; bill short. _Notes._ Song may be compared with the finest efforts of the Blue-headed Vireo with the added charm and mellowness of the song of the Yellow-throated Vireo. (Henshaw.)
Range.--Northern Mexico, north to western Texas, southeastern California, and southern Nevada; winters in Mexico.
=749. Ruby-crowned Kinglet= (_Regulus calendula_). L. 4.4. A conspicuous whitish eye-ring. _Ad._ [Male]. A more or less concealed crown-patch; back olive-green; underparts soiled whitish more or less tinged with buffy; two white wing-bars. _Ad._ [Female] and _Yng._ (Here figured.) Similar, but no crown-patch.
Range.--North America; breeds from the northern border of the United States northward, and south in the Rocky Mountains to Arizona, and in the Sierra Nevada of California; winters from south Carolina and Oregon southward to Central America.
=749a. Sitkan Kinglet= (_R. c. grinnelli_). Similar to No. 749, but more olive-green above; more buffy below.
Range.--Pacific coast; breeds in southern Alaska; winters southward to California.
=470a. Buff-breasted Flycatcher= (_Empidonax fulvifrons pygmæus_). L. 4.7. _Ads._ Below rusty buff; above grayish brown.
Range.--Western Mexico; north in spring to southwestern New Mexico and Arizona.
=586. Texas Sparrow= (_Arremonops rufivirgata_). L. 6.5. _Ads._ Above olive-green, sides of crown brownish, its center grayish; below whitish; bend of wing _yellow_. _Notes._ Song resembles that of the Chipping Sparrow but with somewhat of the sweetness and modulation of that of the Yellow Warbler.
Range.--Eastern Mexico, north to southeastern Texas; casually to Louisiana.
=638. Swainson Warbler= (_Helinaia swainsonii_). L. 5. Bill large; no white in wings or tail. _Ads._ Crown brown, back, wings and tail olive-brown; a whitish line over eye; below whitish tinged with yellow. _Notes._ Song, "a series of clear, ringing whistles, the first four uttered rather slowly and in the same key, the remaining five or six given more rapidly and in an evenly descending scale." (Brewster.)