THEYOPHILUS.— THET0TH0EU8. 89 



11. Thryophilus nigricapillus. 



Thryothorus nigricapillus, Scl. P. Z. S. 1860, p. 84'; Cassia, Pr. Ac. Phil. 1860, p. 193 \ 

 Thryophilus nigricapillus, Scl. & Salv. P.Z. S. 1879, p. 493 '. 

 Thryophilus schottii, Baird, Rev. Am. B. i. p. 133 *. 



T. castaneo similis, sed corpore subtus albo nigro transfasciato, superciliis albis et capitis lateribus albis nigro 

 variegatis differfc. Long, tofca 6-0, alse 2*8, caudse 2-2, rostri a riofcu 1-1, tarsi 1*1. (Descr. maris ex 

 Eemedios, Colombia. Mus. nostr.) 



Eai. Truando, Isthmus of Darien {Schott ^ *). — Colombia ^ ; Ecuador i. 



Thryothorus nigricapillus just enters our region, specimens having been obtained by 

 Dr. A. Schott during Lieut. Michler's exploration of the Isthmus of Darien ^. These 

 specimens were considered to belong to T. nigricapillus by Cassin, but were afterwards 

 described by Prof. Baird as T. 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. Eraser, 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 

 Eemedios and Santa Elena, in the Colombian State of Antioquia, describes the nest as 

 made of soft dry grass and placed in a low bush ^- 



THEYOTHORUS. 



Thriothorus, Vieillot, Analyse, p. 45 (1816). (Type Troglodytes arundinaceus, Vieill., =/%foi« 

 z, 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 Microcer cuius. 



The species comprised in Thryothorus are rather various in form. 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 Fheugopedius, have been 

 placed in another genus, Thryomanes. These distinctions are completely broken 

 down by such birds as T. hyperythrus and T. maculipectus, linking Fheugopedius to 

 Thryothorus ; and as the rest of the members of Thryothorus show more diversity 

 between one another than exists between some of them and T. lairdi, 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. CENTB.-AMBK., ZooL, Aves, Vol. 1, April 1880. 12 



