428 NATATORES. 



windward, and the waves have an apprent motion to leeward, 

 in proportion to the rapidity with which they vibrate. In 

 consequence of that apparent motion, the bird gets credit 

 both for its own real velocity, and the apparent velocity of 

 the waves ; just as when two ships cross each other in dif- 

 ferent courses, upon a side wind, each appears to those on 

 board the other to move at the joint rates of both. 



The storm petrel is not very different from the common 

 swallow, either in size or in appearance, only the bill and point 

 of the tail are very different. The length is almost five 

 inches and a half, and the stretch of the wings fully fifteen. 

 The bill is about half an inch long, rather slender, and with 

 the nasal tube short. The nail part at the tip is not so much 

 bent as in the fork-tailed species. The bill and feet are 

 black, the tarsi being shorter and more slender in proportion 

 than those of the other species. The general tint of the 

 upper plumage is black, very smooth and glossy, and with 

 bluish reflections ; the under part is deep blackish brown ; 

 the rump, some of the feathers at the base of the tail late- 

 rally, and the tips of the greater coverts, and some of the 

 primary quills, are white. The young have the upper 

 plumage with traces of brown. The nests are in holes of tall 

 cliffs, the eggs two in number, and of a white colour. 



Though generally at sea except in the breeding season, and 

 very much during the day even then, these birds are some- 

 times driven inland in the winter months, though it does not 

 appear that they ever find much food there. 



They are bold and familar birds, and may be tamed with- 

 out much difficulty, their food being oil, in which they first 

 bathe the feathers of the breast, and then take it off with the 

 bill. They are exceedingly numerous in some of the northern 

 islands; but their flesh is rank and unpalatable. They are, 

 however, turned to some domestic uses by the islanders. In 



