PETREL. NATATORES. THALASSIDROMA. 535 



in the holes of rocks, or, in default of these, in the burrows Incuba- 

 of rabbits and rats, and under large stones. Most authors 

 have stated it to lay but one egg, and such I believe to be 

 the general law ; but Mr SCARTH *, who found a nest in 

 passing over a track of peat moss near the shore upon an 

 uninhabited islet in Orkney (and to which he was directed 

 by the low purring noise of the female), reports that it con- 

 tained two pure white eggs, of a very large size as compared 

 with the bird ). Upon seizing the old one, he adds, she 

 squirted out of her mouth (nostrils, I presume), an oily sub- 

 stance of a very rancid smell. He took her home, and hav- 

 ing put her into a cage, he offered her worms of various 

 kinds to eat, all of which she refused. After the expiration 

 of four days, he happened to observe that she occasionally 

 drew the feathers of her breast singly across, or rather 

 through, her bill, and appeared to suck an oily substance 

 from them, which induced him to smear her breast with* 

 train oil; and, observing that she greedily sucked the 

 feathers, he repeated the smearing two or three times each 

 day for about a week. He then placed a saucer containing 

 oil in the cage, in which she regularly dipped her breast and 

 then sucked her feathers as before ; and in this way he kept 

 her alive for three months. Some authors have stated that 

 the young, as soon as hatched, are conducted to the water ; 

 but this is a mistake, as they remain in the holes till fully 

 fledged and able to fly, which does not take place for some 

 weeks, and during which time they are fed by the parent 

 birds with oily matter ejected from their stomachs. In the 

 evening, when about to sally forth to procure food, the old 

 ones are very clamorous, making a shrill whistling noise as 

 well as the purring before mentioned ; but during the day 

 they remain silent and quiet in their retreats. From the 

 nature of its food and peculiar economy, this bird is gene- 



* See Volume Thirteenth of the Linnean Transactions, page 617. 

 f They are about equal to those of a Blackbird, although this Petrel but 

 little exceeds a Swallow in dimensions. 



