Perrer. NATATORES. THALASSIDROMA. 535 
in the holes of rocks, or, in default of these, in the burrows 
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 Scarru *, 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 ¢wo 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 mduced 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. 
+ They are about equal to those of a Blackbird, although this Petrel but 
little exceeds a Swallow in dimensions. 
TIncuba- 
tion, &c. 
