608 
SWALLOW TRIBE. 
the nest. In rocky countries they often take possession 
of the clefts on the banks of rivers for their dwelling, and 
sometimes they content themselves with the holes of 
trees. 
Their voice is only a low mutter ; and, while busily pass- 
ing backwards and forwards in the air around their nume- 
rous burrows, they seem at a distance almost similar to 
hiving bees. As they arrive earlier than other species, 
the cold and unsettled weather often drives them for 
refuge into their holes, where they cluster together for 
warmth, and have thus been found almost reduced to a 
state of torpidity. Dwelling thus shut up, they are often 
troubled with swarms of infesting insects, resembling 
fleas, which assemble in great numbers around their 
holes. They begin to depart to the South from the close 
of September to the middle of October. Although they 
avoid dwelling near houses, they do not fly from settled 
vicinities ; and parties of 6 or more, several miles from 
their nests, have been seen skimming through the streets 
of adjacent villages in the province of Normandy. 
In the United States, they are known to breed from 
Georgia to Maine, and were seen by Lewis and Clarke 
near the coasts of the Pacific. They are also equally 
common to Europe and South Africa, and Aristotle re- 
lates that they were numerous in the narrow pass of the 
mountains in Greece. 
The Bank Swallow is 5 inches long, and 10 in alar stretch. Tail 
forked, the outer feather slightly edged with whitish. Wings and 
tail darker than the body. 
SWIFTS. (Cypselus. Itlig.) 
In these birds the bill is extremely short, triangular, cleft to the 
eyes, depressed, the upper mandible slightly notched and curved at 
the point. Nostrils lateral, contiguous, large, partly covered by a 
membrane, leaving a small tubular aperture. Tongue short, wide, 
