BIRDS OF NORTH AND MIDDLE AMERICA. 5 
placed low down on side of skull; maxillo-palatines long and slender 
processes, curved backward; vomer short, with long limbs; nares 
holorhinal; tensor patagii brevis masked passerine or quasi-picarian; 
one pair of tracheo-bronchial muscles, the intrinsic muscles present; 
sterno-trachealis attached to processus vocales; palate sgithog- 
nathous (oscinine); mesorhinium compressed and arched, or ex- 
panded into a flattened oval shield; nostrils conspicuously oper- 
culate; tarsal envelope taxaspidean. 
Externally, the Pteroptochide are characterized by their wren- 
like appearance (though with the bill relatively shorter and stouter 
than in the true wrens), large and strong feet (which are excessively 
developed in some genera), short, very concave, and much rounded 
wing (with 10 primaries), and, usually, short or very short tail, which 
is usually carried erect or thrown forward. Of terrestrial or semi- 
terrestrial habits they are well adapted to hopping or running on the 
ground; but their power of flight is very limited, the birds of this 
family being able to fly but a short distance. They are very active, 
inquisitive, and noisy birds, and their notes are varied and remarkable, 
but harsh and loud rather than musical. 
The Pteroptochide are peculiar to the more southern portions of 
the Neotropical Region, the high mountains of Costa Rica, where 
a single representative occurs, being the northern limit; only seven 
of the thirty-one species and two of the eight known genera occur in 
the elevated districts of Colombia, the remainder occurring in the 
Andean district of Ecuador, Peru, and Chile, and thence to the 
Falkland Islands, Argentina, and southeastern Brazil, two of the Co- 
lombian species (belonging to separate genera) extending as far east- 
ward as the higher mountains of Venezuela. 
In Volume XV of the Catalogue of the Birds in the British Mu- 
seum (1890, pp. 337-352) Dr. Sclater recognizes eight genera and 
twenty-one species; but Dr. Sharpe, in his Hand List of the Genera 
and Species of Birds (Vol. ITI, 1901, pp. 4-7), increases the number 
of species to thirty-one. 
Genus SCYTALOPUS Gould. 
Scytalopus Goutp, Proc. Zool. Soc. Lond., 1836, 89. (Type, S. fuscus Gould= 
Motacilla magellanica Gmelin.) 
Sylviaxis Lesson, Rev. Zool., 1840, 274. (Type, S. guttatus Lesson=unidenti- 
fied species). 
Agathopus ScuateR, Proc. Zool. Soc. Lond., 1858, 69. (Type, A. micropterus 
Sclater= Merulavis analis Lafresnaye?) 
Small wren-like Pteroptochide (length about 100 to 130 mm.) 
with the mesorhinium compressed and slightly arched, loral feathers 
short, tail much shorter than wing, tarsal envelope distinctly scutel- 
late, and hind claw strongly curved and shorter than the digit. 
