598 
SWALLOW TRIBE. 
and a little hooked at the point. Nostrils basal, oblong, behind 
partly closed by a membrane, and covered by the advancing feathers 
of the frontlet. Tongue short, bifid. Feet short, and slender ; middle 
toe longer than the subequal lateral ones, united with the outer to 
the first articulation, middle toe-nail largest. First primary longest. 
Tail of 12 feathers, and generally forked. 
These birds are remarkable for their sociability, living generally in 
families, constructing their nests together, and often rendering mu- 
tual assistance in its formation ; they also assemble and migrate in 
large flocks. Some build in hollow trees, barns, out-buildings, chim- 
neys, and even on the ground, or the larger branches of trees ; the ex- 
ternal part of the nestis fortified with hardening materials, the interi- 
or lined with soft substances. Constantly paired, they rear several 
broods in the season, and unite in the labor of rearing the young. 
They frequent watery places in pursuit of winged insects, which 
they take with agility, swimming as it were in the air ; they likewise 
skim over the surface of waters, and drink and bathe even without 
alighting, the air being almost their peculiar element. In fair weath- 
er they delight to ascend into the elevated regions of the atmos- 
phere ; but previous to rain, which they thus prognosticate, they 
lower their flight, and at length sail near the surface of the earth. 
They inhabit every region, and moult once a year, in the depth of 
our winter, and while in their tropical asylum, 
PURPLE MARTIN. 
(Hir undo purpurea , L. Wilson, v. p. 58. pi. 39. fig. 1. and 2. Aud. 
pi. 22. Orn. i. p. 115. Phil. Museum, No. 2645, 2646.) 
Sr. Charact. — Dark bluish-purple, and glossy ; wings and forked 
tail brownish-black. — Female and young bluish-brown ; belly 
whitish. 
According to the progress of the season in the very 
different climates of the United States, is measured the 
arrival of this welcome messenger of spring. Around the 
city of New Orleans, for example, the Purple Martin is 
seen from the 1st to the 9th of February. At the Falls 
of the Ohio they are not seen before the middle of March, 
and do not arrive in the vicinity of Philadelphia until the 
first week in April ; on the 25th of that month or later, 
