522 LARID^. 



of rocks, and laying one white egg of a roundish oval form, 

 large for the size of the bird, measuring one inch four lines in 

 length, and eleven lines in breadth. 



Mr. Audubon, who has enjoyed many opportunities of ob- 

 serving these swallow-like Petrels during his ornithological 

 researches in various parts of North America, as well as on 

 his various voyages across the Atlantic, says, " The species of 

 this genus with which I am acquainted, all ramble over the 

 seas, both by night and by day, until the breeding-season 

 commences ; then they remain in their burrows, under rocks, 

 or in their fissures, until towards sunset, when they start off 

 in search of food, returning to their mates, or young, in the 

 morning, and feeding them then. When you pass close to 

 the rocks in which they are, you easily hear their shrill, 

 querulous notes ; but the report of a gun silences them at 

 once, and induces those on the ledges to betake themselves 

 to their holes. The Forked-tailed Petrel emits its notes 

 night and day, and at not very long intervals, although it is 

 less noisy than Wilson''s Petrel. They resemble the sylla- 

 bles pewr-wit, pewr-wit. Its flight differs from that of the 

 other two species, it being performed in broader wheelings, 

 and with firmer flappings. It is more shy than the other 

 species, and when it wheels off after having approached the 

 stern of a ship, its wanderings are much more extended be- 

 fore it returns. I have never seen it fly close around a 

 vessel, as the others are in the habit of doing, especially at 

 the approach of night ; nor do I think that it ever alights on 

 the rigging of ships, but spends the hours of darkness either 

 on the water, or on low rocks or islands. It also less fre- 

 quently alights on the water, or pats it with its feet, probably 

 on account of the shortness of its legs, although it frequently 

 allows them to hang down. In this it resembles the Storm 

 Petrel, and Wilson's Petrel has a similar habit during calm 

 weather. I have seen all the three species immerse their 



