a. Thryothorus.
T. ludovicianus. Tail-feathers reddish-brown, barred with black. Greater wing-coverts spotted with whitish.
Beneath yellow-whitish, washed occasionally with rusty. Sides plain. Bill from nostril, .45. Length, 6.00. Hab. Eastern Province United States … var. ludovicianus.
Beneath rufous; lighter on throat and along median line. Sides obsoletely barred with dusky. Bill from nostril, .56. Length, 5.25. Hab. Lower Rio Grande … var. berlandieri.
b. Telmatodytes.
T. bewickii. Tail-feathers, except central, black; the exposed surface and tips only varied with white. Length, 5.50.
Above dark rufous-brown; beneath plumbeous-white; flanks tinged with brown. Rump and exposed secondaries distinctly banded. Quills and middle tail-feathers brownish-black. Length from nostril, .39; along gape, .70. Hab. Eastern Province United States … var. bewickii.
Above ashy-brown; beneath, including flanks, clear white; rump ashy, and, like secondaries, very obsoletely barred. Quills and middle tail-feathers grayish-brown. Hab. Southern border of United States, into Mexico … var. leucogaster.
Colors intermediate between the two last. Bill longer, from nostril, .50, from gape, .81. Hab. Pacific Province … var. spilurus.