284 REVIEW OF AMERICAN BIRDS. [PART I. 
Cotyle, however, the relationship, except in coloration, is very slight, — 
as the nostrils are superior, without overhanging membrane as in 
Cotyle ; the lower end of tarsus destitute of feathers (the upper, on 
the contrary, being provided with them); the lateral claws short, 
much curved, and not reaching beyond the base of the middle. The 
bill is much stouter, and the body more robust; the edge of wing 
without hooks, in these respects differing from Stelgidopteryx. 
With somewhat the fulness of form of Progne, the bill resembles 
the latter in having the nostrils superior, exposed, and without over- 
hanging membrane. The frontal feathers are soft, but with short 
bristles lining the base of the upper jaw, and a few on the side of the 
lower, but none in the chin. The bill is more depressed than in 
Progne, but similarly shaped ; the lower edge of the upper mandible 
much sinuated, or quite convex to the anterior extremity of the 
nostril, and then passing into an equally concave curve to the tip. 
Both jaws are more depressed, and their upper outlines less convex, 
especially towards the base, than in Progne. The feet are weaker, 
but the adhesion of the toes much as in Progne—the basal joint of 
the median being free for about half internally, a little less externally. 
The upper joint of the tarsus is covered with feathers, which are 
attached along the inner edge in a narrow line for half the length, 
or more than half the length (even three-fourths). This feature is 
quite peculiar to Phxoprogne, not existing at all in Progne, nor to 
anything like the same extent in any other American Swallows. The 
tarsal scutelle are so much fused as to be almost undistinguishable. 
The wings are more falcate, the feathers broader and less curved 
than in Progne; the tail but slightly forked; the lateral feathers 
without the gradual attenuation of Progne. 
The species of this group belong strictly to South America, but 
are not well determined. I give below the two which seem to be 
contained in the specimens which I have examined. None have 
any metallic gloss, as in Progne—resembling in color Cotyle and 
Stelgidopleryx more than any other genera. The form is more that 
of Petrochelidon, the nostrils being equally superior and uncovered, 
and the tail is somewhat similar. The bill is, however, much stouter, 
longer, and the commissure is sinuated, not nearly straight. 
Synopsis of Species. 
Common CHARAcTERS.—Above and along sides dull smoky brown, 
without metallic lustre; a fainter pectoral band of the same. 
Rest of under parts white. 
Sides of neck white, passing around on the nape into a narrow 
a 
