STELGIDOPTERYX. 313 
verging. Frontal feathers soft, and, like chin, without bristles. Tarsi equal 
to middle toe without claw; the upper end covered with feathers all round, 
none at lower end. Basal joint of middle toe adherent externally nearly to 
end; internally, scarcely half. Lateral toes about equal, their claws not 
reaching beyond base of middle claw. Tail slightly emarginate ; the feathers 
broad, and obliquely rounded at end. Edge of wing rough to the touch; the 
shafts of the fibrille of outer web of outer primary prolonged and bent at 
right angles into a short stiff hook. 
Color dull brown above. 
The great peculiarity in this genus consists in the remarkable 
roughness of the edge of the wing, said to occur also in Psalido- 
procne, Cab. The object is uncertain, but is probably to enable the 
bird to secure a foothold on vertical or inclined rocks, among or 
on which it makes its nest. A favorite breeding place of S. serri- 
pennis is in the piers and abutments of bridges, and these hooks 
might render essential aid in entering into their holes. 
The birds of this genus have usually been referred to Cotyle, 
which, however, they resemble only in color. The nostrils are ex- 
posed, instead of being overhung; the tarsus is bare below, not 
feathered, and the lateral claws are considerably curved, and not 
reaching beyond the base of the lateral, asin Cotyle. The structure 
of the wing is very different. 
According to Cabanis, Psaudoprocne (P. cypselina, Cab. of 
Africa) has the same structure of wing, but it seems to differ in 
having the tail deeply forked, as in Alticora ; the toes and nails even 
shorter than in Aéticora, not longer; and in having the outer toe 
shorter than the inner, instead of equal to it. 
The genus has a wide range, extending from British America to 
Brazil, and probably Ecuador. 
as his description of the tail and its under coverts, at least, does not apply at 
all. Brisson’s article is evidently copied from Feuillé (1725), a very vague 
author, as likely to call a Cuckoo or Flycatcher ‘“‘Hirundo” as anything else. 
This species is much in form like A. cyanoleuca, but considerably larger. 
I have little doubt that the A. cyanophea, of Cabanis, is the young bird of this 
species, aS a specimen in the museum of the Philadelphia Academy, from 
Bogota, agrees exactly with Cabanis’s description, and is hardly to be distin- 
guished, except in its evident immaturity, from the Academy-type of Cassin’s 
Petrochelidon murina, from Ecuador. It is probably closely related to the H. 
andecola, of D’Orb. & Lafr. Syn. Av. 1837, 69 (La Paz), but differs somewhat. 
