BIRDS OP 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 segithog- 

 nathous (oscinine); mesorhinium compressed and arched, or ex- 

 panded into a flattened oval shield; nostrils conspicuously oper- 

 culate; tarsal envelope taxaspidean. 



Externally, the Pteroptochidas 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 Pteroptochidse 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. Ill, 1901, pp. 4-7), increases the number 

 of species to thirty-one. 



Genus SCYTALOPUS Gould. 



Scytalopus Gould, Proc. Zool. Soc. Loud., 1836, 89. (Type, S./uscus Gould= 

 Motacilla niagellanica Gmelin.) 



Sylviaxis Lesson, Rev. Zool., 1840, 274. (Type, S. guttatus Lesaon= unidenti- 

 fied species). 



Agathopus Sclater, Proc. Zool. Soc. Loud., 1858, 69. (Type, A. micropterus 

 Sclater= Merulaxis analis Lafresnaye?) 



Small wren-like Pteroptochidae (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. 



