Page:Voyage in search of La Perouse, volume 1 (Stockdale).djvu/160

150 the air; when they frequently ue their feet alo, which, being webbed, erve them to make everal trokes againt the water, in order to raie themelves out of it. This impulion being once given, they have no more occaion to trike their wings together, but hold them very widely expanded, whilt they ail along, balancing their bodies alternately from right to left, and kimming wiftly over the urface of the ea in quet of their food. This mode of poiing themelves in the air undoubtedly erves to accelerate their flight, but one can hardly uppoe it to be ufficient for upporting them above the urface. Perhaps ome imperceptible tremulous motion of their feathers may be the principal caue of their extraordinary mode of flying. If that be the cae, they mut be provided with ome particular mucles adapted for the purpoe; on which account I think that the tructure of the albatros deerves to be very attentively invetigated by anatomits.

The puffins of Buffon (procellaria puffinus), were very numerous in thee eas. The flight of this bird is performed in a manner analogous to that of the albatros, for he often kims along for a great length of time without any perceptible motion of his wings: it is only when he changes his oblique poition from one ide to the other that