PROGNE. 271 
Lateral claws lengthened, reaching beyond 
base of middle claw. 
Tail slightly forked. Color dull brown 
above; beneath white, with brown 
pectoral collar . : ° : - Cotyle. 
Tarsus long ; equal to middle toe and half claw ; entirely 
bare. Tail considerably forked, about equal to 
closed wing. Color green above; white beneath . Callichelodon. 
The arrangement and subordination of forms which I propose to 
adopt in the further consideration of the subject, as expressing more 
nearly the affinities of the American Hirundinide, is as follows :— 
Progne. Largest size. Commissure sinuated and much arched from base. 
(Ouly here). Nostrils superior. Frontal feathers soft. 
Subdivisions Progne, Pheoprogne. 
Petrochelidon. Commissure almost straight to near tip. Bill large. Nos- 
trils superior, not? overhung. Frontal feathers bristly. Legs bare. (Only 
here.) Rump rufous. 
Subdivision Petrochelidon. 
Chelidon. Nostrils superior, but slightly overhung. Legs feathered to claw. 
(Here only.) (European exclusively.) Rump and under parts white. 
Hirundo. Nostrils*lateral; overhung by membrane. Lower end of tarsus 
bare. Rump white, or else like the back. Crissum white, or rufous. 
Subdivisions Hirundo, Tachycineta, Callichelidon. 
Atticora. Smallest size. Nostrils superior, not overhung. Bill very small. 
Crissum mostly black. Middle toe usually adherent beyond basal joint, 
except Pygochelidon. (Here only.) 
Subdivisions (Cherameca?), Pygochelidon, Atticora, Notiochelidon, 
Neochelidon. 
Stelgidopteryx. Nostrils superior, not overhung. Edge of wing scratchy 
and rough. (Here only.) Crissum white. 
Subdivisions Stelgidopteryx (Psalidoprocne?). 
Cotyle. Nostrils lateral, overhung by membrane. Lower end of tarsus with 
a tuft of feathers, and lateral claws reaching beyond base of middle. 
(Here only.) Crissum white. 
Subdivision Cotyle. 
PROGNE, Bort. 
4 | Progne, Bors, Isis, 1826, 971. (Type Hirundo purpurea, L. (H. subis, L.)) 
- —Barrp, Birds N. Am. 1858, 314. 
Body stout. Bill robust, lengthened ; lower or commissural edge of max- 
illa sinuated, decidedly convex for basal half, then as concave to the tip, the 
