20 CANARY ISLANDS. 



tail, which renders their flight and carriage analogous to 

 those of swallows. Their bills are pointed, compressed, 

 and straight, without curve or projection ; their nostrils, 

 situated near the base of the bill, are oblong and pierced 

 quite through ; the membranes that unite their toes, are 

 deeply emarginate, in consequence of which, they swim 

 but seldom. They fly over the waves in every direction 

 with great velocity, uttering, at the same time, shrill cries, 

 and skilfully dipping from the water mollusca and small 

 fishes upon which they feed. 



The petrils are particularly designated by sailors under 

 the name of Mother Carey's Chickens. They are also 

 sometimes called Storm Finches, Stormy Petrels, and 

 Devil's Birds. The most common species on the Atlantic 

 is the Thalassidroma wilsonii of Bonapart. It is about 

 the size of a common swallow, and has the general appear- 

 ance of that bird. Its color is brown, except the rump, 

 w^hich is white, and a white line on the end of the great 

 wing-coverts. At all seasons they keep far out at sea, and 

 often skip along the hollows of the waves with incredible 

 swiftness, and sometimes light upon their summits, braving 

 the utmost fury of the tempests. As they appear to run on 

 the surface of the water, which they effect by the aid of 

 their wings, they are called petrels, from the allusion of 

 Peter's walking on the water. 



" These petrels are said to breed in great numbers on the 

 rocky shores of the Bahama and the Bermuda Islands, 

 and along some parts of East Florida and Cuba. Mr. 

 Audubon informs me* that they also breed in large flocks 

 on the mud and sand islands off Cape SabJe, in Nova 

 Scotia, burrowing downward from the surface to the depth 

 of a foot or more. They also employ the holes and cavi- 

 ties of rocks near the sea for this purpose. The eggs, 

 according to Mr. Audubon, are three, white and translu- 

 cent. After the period of incubation, they return to feed 

 their young only during the night, with the oily food which 

 they raise from their stomachs. At these times they are 

 heard through most part of the night, making a continued 



Professor Xuttall. 



