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 

 scutelte alpng the anterior face of the tarsus, and a longitudinal 

 plate on each side, meeting but not coalescing behind. The anterior 

 scutellse 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 scutelte, and usually entire, 

 except perhaps at the lower extremity. 



In comparing the wings of the Hirundinidm with those of the 

 Gypselidse, 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 Hirundinidm in America — some more 

 or less local, others with wide range. One of these species — Gotyle 

 riparia — is believed to be identical with a European ; and one — H. 

 erythrog aster Qiorreorum, also, if distinct) — is generically insepa- 

 rable from the European H. ruslica. 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 Hirundinidse are widely diffused 

 over the whole continent — the Atticora group alone not extending 

 north of Central America. 



In America we have nothing corresponding to the European 

 genus Ghelidon (C. urhica), characterized by having the tarsi and 

 toes covered with feathers to the claws, as in Lagopus (the soles 

 bare). 



The American Hirundinidse 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 cnlmen and commissure much decurved, so that the 

 chord of the latter includes lower jaw, in Progne and Phceoprogne. In 



