Sexes dissimilar.
Merula. Similar to Turdus. Male usually more or less black, especially on the head; females brownish, often with streaked throats. Bill distinctly notched.
Hesperocichla. Similar to Turdus. Male reddish beneath, with a black collar. Bill without notch.
Subgenus HYLOCICHLA, Baird.
Hylocichla, Baird (s. g.), Rev. Am. Birds, 1864, 12. (Type, Turdus mustelinus.)
Turdus mustelinus.
1570
The essential characters of Hylocichla have already been given. The subgenus includes the small North American species, with Turdus mustelinus, Gm., at the head as type, which are closely connected on the one side with Catharus, by their lengthened tarsi, and with Turdus by the shape of the wing. The bills are shorter, more depressed, and broader at base than in typical Turdus, so much so that the species have frequently been described under Muscicapa.
It is not at all improbable that naturalists may ultimately conclude to consider the group as of generic rank.
In this group there appears to be five well-marked forms or “species.” They are, mustelinus, Gm., pallasi, Caban., fuscescens, Steph., swainsoni,