268 REVIEW OF AMERICAN BIRDS. [PART I. | 
to make out, owing to a tendency to fusion of the plates, although 
not essentially different from most Oscines. There is a series of 
seutelle along the anterior face of the tarsus, and a longitudinal — 
plate on each side, meeting but not coalescing behind. The anterior — 
scutellae sometimes appear to fuse into the outer lateral plate; or 
sometimes the latter is more or less subdivided; the inner plate is — 
generally more distinct from the anterior scutelle, and usually entire, — 
except perhaps at the lower extremity. 
In comparing the wings of the Hirundinide with those of the 
Cypselide, we readily notice one of the essential characters of the 
Oscines, viz., that the greater wing coverts hide only half or less 
than half of the secondary quills, instead of reaching much beyond 
their middle, or nearly to the end. (See Sundevall, Ornith. Syst.) 
There are many species of Hirundinide in America—some more 
or less local, others with wide range. One of these species— Cotyle 
riparia—is believed to be identical with a European; and one—Z. 
erythrogaster (horreorum, also, if distinct)—is generically insepa- 
rable from the European ZZ. rustica. The other genera are not 
represented in Europe, though Petrochelidon has at least one Aus- 
tralian example (P. nigricans). 
Most of the genera of American Hirundinide are widely diffused 
over the whole continent—the Afticora group alone not extending 
north of Central America. 
In America we have nothing corresponding to the European 
genus Chelidon (C. urbica), characterized by having the tarsi and 
toes covered with feathers to the claws, as in Lagopus (the soles 
bare). 
The American Hirundinidz vary considerably in reference to the 
character of the nostrils, whether superior or lateral, with or without 
membrane: the comparative length of tarsus, toes, and claws: the 
amount of adhesion of middle toe to lateral: the feathering of the 
tarsus: depth of fork of tail, etc., these features applying to the 
different groups somewhat as follows :— 
Nostrils superior; broadly oval; not overhung by membrane on inner and 
upper side, especially anteriorly: Progne, Petrochelidon, Atticora, Stelgi- 
dopteryx. 
Nostrils lateral; overhung or bordered internally by membrane, which is 
straight edged above or internally, and directed either parallel with axis 
of bill, or diverging from it: Hirundo, Tachycineta, and all other Ameri- 
can genera, except those of first section. 
Bill very stout; the culmen and commissure much decurved, so that the 
chord of the latter includes lower jaw, in Progne and Phaoprogne. In 
———————— eee 
ee. 
Te? Poe 
