The characters of this genus are sufficiently indicated in the synopsis on [page 131]. They come very close to those of Thryothorus, the nostrils, especially, being linear and overhung by a scale. In this respect both differ from Thryophilus of Middle America. The bill is shorter or not longer than the head; straight, slender, and without notch. The tail is graduated, and shorter than the much rounded wings, the feathers narrow. The light superciliary line of Thryothorus is almost entirely wanting.
Species and Varieties.
a. Troglodytes.
Tail and wings about equal.
T. ædon. Beneath grayish-white. Crissum and flanks distinctly barred. Wing-coverts spotted with whitish. Dark bars of tail about half the width of their interspaces.
First primary nearly half the longest. Color above dark-brown, rufous towards tail. Hab. Eastern Province United States … var. ædon.
Wing similar. Above paler brown. Hab. Eastern Mexico, from Rio Grande southward … var. aztecus.
First primary half the second. Above paler brown. Hab. Middle and Western Province United States … var. parkmanni.
Tail very short; only about two thirds the wing.