THRYOPHILUS.—THRYOTHORUS. 89 
11. Thryophilus nigricapillus. 
Thryothorus nigricapillus, Scl. P. Z. S. 1860, p. 841; Cassin, Pr. Ac. Phil. 1860, p- 193°. 
Thryophilus nigricapillus, Scl. & Salv. P.Z. 8. 1879, p. 493 *. 
Thryophilus schottii, Baird, Rev. Am. B. i. p. 183 *. 
ZT’. castaneo similis, sed corpore subtus albo nigro transfasciato, superciliis albis et capitis lateribus albis nigro 
variegatis differt. Long. tota 6:0, ale 2°8, caude 2-2, rostri a rictu 1:1, tarsi 1-1. (Descr. maris ex 
Remedios, Colombia. Mus. nostr.) 
Hab. Truando, Isthmus of Darien (Schott 2+).—Cotomsia 3; Ecuapor }. 
Thryothorus nigricapillus just enters our region, specimens having been obtained by 
Dr. A. Schott during Lieut. Michler’s exploration of the Isthmus of Darien 2. These 
specimens were considered to belong to 7. nigricapillus by Cassin, but were afterwards 
described by Prof. Baird as 7. schottii, on account of the throat being barred with 
black instead of being pure white, as is usual in the Ecuadorian bird. But the acqui- 
sition of a better series of specimens of this species shows that this character is variable 
and therefore not of much value; we have accordingly reunited the Darien bird to 
T. nigricapillus. Fraser, the discoverer of the species at Nanegal in Ecuador }, says 
that the irides are red, the bill black above, blue below, the legs and feet lead-colour, 
and that the gizzard of his specimens contained insects. Salmon, who obtained it at 
Remedios and Santa Elena, in the Colombian State of Antioquia, describes the nest as 
made of soft dry grass and placed in a low bush®. 
THRYOTHORUS. 
Thriothorus, Vieillot, Analyse, p. 45 (1816). (Type Troglodytes arundinaceus, Vieill., = Sylvia 
ludoviciana, Lath.) Cf. Baird, Rev. Am. B. i. p. 120. 
The nostril in birds of this genus is covered by a thickened overhanging membrane, 
leaving the nasal opening an elongated slit, lying along the anterior portion of the 
lower edge of the nasal fossa. This nostril is very different in shape from that of 
Thryophilus, in which genus it is an oval and open, without any covering. The tail is 
long, wide, and rounded, differing in these respects from that of Microcerculus. 
The species comprised in Thryothorus are rather various inform. One group, having 
very strong arched bills, has been treated by Prof. Baird as a separate genus, Pheugo- 
pedius; whilst the birds with slender bills, the opposite of Pheugopedius, have been 
placed in another genus, Thryomanes. These distinctions are completely broken 
down by such birds as 7. hyperythrus and T. maculipectus, linking Pheugopedius to 
Thryothorus; and as the rest of the members of Thryothorus show more diversity 
between one another than exists between some of them and 7’. dairdi, we have thought 
it best to retain all under one genus, Thryothorus, distinguished by its well-developed 
tail and by the form of the nostrils. In splitting up the genus into minor sections 
BIOL. CENTR.-AMER., Zool., Aves, Vol. 1, Apri] 1880. 12 
