_Progne_, BOIE, Isis, 1826, 971. (Type, _Hirundo purpurea_ vel
_subis_, L.)—BAIRD, Birds N. Am. 1858, 314.
GEN. CHAR. Body stout. Bill robust, lengthened; lower or commissural
edge of maxilla sinuated, decidedly convex for basal half, then as
concave to the tip, the lower mandible falling within its chord.
Nostrils superior, broadly open, and nearly circular, without any
adjacent membrane, the edges rounded. Legs stout. Tarsus equal to
middle toe without claw; the joint feathered; lateral toes about
equal; the basal joint of the middle toe half free internally, rather
less so externally. Claws strong, much curved. Nest in hollow trees.
Eggs white.
The species of this genus are the most powerful and robust of the
Swallows. Some are entirely glossy-black, others whitish below. The
following diagnosis will show the relationship of the several forms
usually recognized as distinct species:—
Species and Varieties.
P. subis. Above lustrous blue-black; beneath lustrous blue-black or brownish-gray,
uniform, or with the abdomen and crissum white, or whitish. Females
always with the throat and jugulum gray.
A. Adult males entirely steel-blue.
_a._ Females and young males with the abdomen pure white.
_Feathers about the anus smoky-gray beneath the surface._
Wing about 6.00; fork of tail, .80 deep. ♀ and _Juv._
Abdominal and crissal feathers always with dusky shafts, and
with the concealed portion grayish. Forehead and nape hoary
grayish. _Hab._ Continental North America, south into
Northern Mexico … var. _subis_.
Wing, 5.25; fork of tail considerably less. ♀ and _Juv._
unknown. _Hab._ Galapagos … var. _concolor_.[63]
Wing, 5.80; fork of tail, 1.10 deep. ♀ and _Juv._ unknown.
_Hab._ Chili … var. _furcata_.[64]
_Feathers about the anus snowy-white beneath the surface._
Wing. 5.50; fork of tail, .90 deep. ♀ and _juv._ Abdominal
and crissal feathers entirely snowy-white,—never with dusky
shafts (except ♂ _juv._ in transition). Forehead dusky
grayish-brown; nape steel-blue. _Hab._ Cuba and Florida Keys …
var. _cryptoleuca_.
_b._ Females and young with the abdomen dusky grayish-brown.
Wing, 5.50; fork of tail, .80. ♀. Lower parts dusky
grayish-brown, the feathers bordered with lighter grayish,
producing a squamate appearance. _Juv._ similar, but feathers
of the upper parts bordered with whitish. _Hab._ Paraguay
(Vermejo River) … var. _elegans_.[65]
B. Adult males with the abdomen and crissum pure white.
_a._ Lower tail-coverts with the shafts pure white. ♂ (adult)
with the throat, jugulum, and sides steel-blue.
♀ and _juv._ scarcely distinguishable from those of
_cryptoleuca_. _Hab._ Porto Rico and Jamaica (St. Domingo
also?) … var. _dominicensis_.[66]
_b._ Lower tail-coverts with their shafts dusky. ♂ (adult) with
throat, jugulum, and sides brownish-gray.
Sides of the jugulum with a blue-black patch in the ♂. Wing,
5.50; fork of tail, .70 deep. _Hab._ Bolivia …
var. _domestica_.[67]
Sides of the jugulum without a blue-black patch in the ♂.
Wing, 5.20; fork of tail, .55 deep. _Hab._ Middle America,
from Southern Mexico to New Granada … var. _leucogaster_.[68]
Progne subis, BAIRD.