230 NATURAL HISTORY OF SELEORINE. 
ground and water, and distinguish themselves by rapid turns and 
quick evolutions ; swifts dash round in circles ; and the bank-martin 
moves with frequent vacillations like a butterfly. Most of the small 
birds fly by jerks, rising and falling as they advance. Most small 
birds hop; but wagtails and larks walk, moving their legs alter- 
nately. Skylarks rise and fall perpendicularly as they sing ; 
woodlarks hang poised in the air; and tit-larks rise and fall in 
large curves, singing in their descent. The white-throat uses odd 
jerks and gesticulations over the tops of hedges and bushes. All 
the duck-kind waddle ; divers and auks walk as if fettered, and 
stand erect on their tails: these are the compedes of Linnzus. 
Geese and cranes, and most wild fowls, move in figured flights, 
often changing their position. The secondary remzges of Tringe, 
wild ducks, and some others, are very long, and give their wings, 
when in motion, an hooked appearance. Dabchicks, moor-hens, 
and coots, fly erect, with their legs hanging down, and hardly make 
any dispatch; the reason is plain, their wings are placed too 
forward out of the true.centre of gravity ; as the legs of auks and 
divers are situated too backward, 
