A. Black cheek-stripes involving eyelid only on upper border of eye, and not meeting across the forehead. A crescentic patch of white in the black below the eye; upper edge of black stripe behind the eye bordered by hoary whitish. Breast and belly always with distinct, transverse waved lines of dusky. Bill, when mature, entirely black. Length about 10 inches.
Above light ash. Upper tail-coverts and forehead much paler than the back, the former without waved lines. Axillars whitish.
Inner webs of secondaries paler towards edges, but not of well-defined white. Concealed bases of tail-feathers, except sixth, white. Tarsus shorter than the gape of mouth. Length, 10.00; extent, 14.50; wing, 4.70; tail, 4.70; bill above, .85; tarsus, .93 … borealis.
B. Black cheek-stripes not involving upper border of eye or upper eyelid, which is whitish, and not meeting across the forehead, its upper edge behind the eye with scarcely a lighter border. No patch of white on lower eyelid. Under parts unvaried white; in female obscurely waved. Base of under mandible whitish. Length about 9 inches.
Above light ash. Upper tail-coverts and forehead decidedly paler than the back. Axillars whitish.
Inner webs of all secondaries (except innermost) white to shaft, except for less than terminal half, which is black along the shaft. Concealed base of tail white, except on sixth feather. Tarsus equal to the gape … excubitor.
C. Black cheek-stripes involving upper eyelid, as in A, but without patch of white below the eye; meeting in a narrow, sometimes inconspicuous, line across the forehead, its upper edge behind the eye not bordered by lighter. Beneath plain white, or very obscurely waved in ludovicianus (the female?). Bill, when mature, entirely black. Length about 8.50 inches.
Above dark plumbeous-ash. Upper tail-coverts and forehead scarcely paler than the back. Sides and breast tinged with bluish-gray.
Black of loral space rather hoary along upper border. Frontal dark line inappreciable or wanting. Inner webs of secondaries paler only along the marginal half, and not abruptly white. Axillars plumbeous. Tail-feathers, except the innermost, with a concealed well-defined white patch at base, largest on the more exterior one. Bill from nostril, .50. Under parts often with very obscure faint waved lines (in the female?). White patch on wing reaching about to middle of first primary. Tarsus equal to the gape. Length, 8.50; wing, 3.72; tail, 4.10; bill above, .82; tarsus, 1.00 … ludovicianus.
Black of loral space without any lightening above it. Frontal black band well marked. Inner webs of secondaries (except innermost) pure white to shaft, except along rather more than terminal half, where the shaft is bordered by black. Axillars whitish. Tail-feathers black to base, except the loose fibres, which are grayish. Bill from nostril, .60. Under parts without waved lines. White patch on wing reaching nearly opposite to end of first primary. Tarsus about equal to the gape. Length, 8.75; wing, 4.20; tail, 4.40; bill above, 1.00; tarsus, 1.20 … elegans.