Dr. Coues regards its habits as more like those of the true Ground Warblers than those of the other species of this group. It shows a decided preference for thickets and copses, rather than for high open woods, and is also an exceedingly shy and retiring species. To the extreme difficulty of observing or procuring it Dr. Coues attributes its having so long remained unnoticed. It is described as exceedingly active in all its motions, and quite as restless as a _Polioptila_, to which class, in its colors, it also bears a close resemblance. The only note Dr. Coues ever heard it utter was a quick and often repeated _tsip_, as slender and as wiry as that of a Gnatcatcher. Dr. Cooper, however, has described its song as rich and pleasing, the little performer being mounted on the top of some mezquite or other bush. Dr. Cooper supposes this species to breed, not in the Colorado Valley, but in the more mountainous regions. Dr. Coues hazards the conjecture that this bird builds in low bushes. Should it prove so, it would in this respect differ from all the other members of this well-marked group, and from the other Ground Warblers, which, in its general habits, it so much resembles. Helminthophaga celata, var. celata, BAIRD. ORANGE-CROWNED WARBLER. _Sylvia celata_, SAY, Long’s Exp. R. Mts. I, 1823, 169.—BON. Am. Orn. I, pl. v, fig. 2.—AUD. Orn. Biog. II, pl. clxxviii. _Sylvicola cel._ RICH. _Vermivora cel._ JARD. _Helinaia cel._ AUD. Birds Am. II, pl. cxii. _Helmitherus cel._ BON.—SCLATER, P. Z. S. 1857, 212 (Orizaba). _Helminthophaga cel._ BAIRD, Birds N. Am. 1858, 257; Rev. Am. Birds, I, 1865, 176 (in part).—DALL & BANNISTER (Alaska).—SCLATER, P. Z. S. 1858, 298 (Oaxaca, December); 1859, 373; 1862, 19 (La Parada). _H. celata_, var. _celata_, RIDGW. Rept. U. S. Geol. Expl. 40th Par. SP. CHAR. Above grayish olive-green, rather brighter on the rump. Beneath entirely greenish yellowish-white, except a little whitish about the anus; the sides tinged with grayish-olivaceous. A concealed patch of pale orange-rufous on the crown, hidden by the grayish tips to the feathers. Eyelids and an obscure superciliary line yellowish-white, a dusky obscure streak through the eye. Inner webs of tail-feathers broadly edged with white. _Female_ with little or none of the orange on the crown, and the white edgings to inner webs of tail-feathers. _Young_ lacking the orange entirely, and with two fulvous-whitish bands on the wing. Length, 4.70; wing, 2.25; tail, 2.00. HAB. Middle Province of North America; Yukon and McKenzie River district. Very rare in the Eastern Province of United States; Mexico in winter; Oaxaca, La Parada, (SCLATER); Orizaba, winter (SUMICHRAST).