564 CLASS AVES. 



spread everywhere, and are met by navigators in all 

 seas. They may be known by their thumb being 

 free, or by its absence altogether ; by their very long 

 wings ; and by their bill without indentations, but 

 bent at the extremity in the first genera, and simply 

 pointed in the rest. Their lower larynx has but one 

 proper muscle on each side ; their gizzard is muscular, 

 and their coecum short. 



The Petrels, Porocellaria, Lin. 



Have the bill bent at the end, the extremity of which 

 seems to consist of a piece articulated to the rest ; 

 their nostrils are united in one tube, imbedded in the 

 back of the upper mandible ; their feet have only, in 

 place of a thumb, a claw or spur implanted in the heel. 

 Of all the palmipedes, these keep themselves the most 

 distant from the shore ; and hence when a tempest 

 happens they are frequently obliged to seek for 

 refuge on rocks in the sea or on vessels, whence 

 they have derived the name of tempest birds. The 

 French name. Petit Pierre, is taken from their habit 

 of walking on the water by the help of their wings. 

 They make their nests in the clefts of rocks, and 

 eject on those who attack them an oily liquid, with 

 which it seems their stomach is always filled. Most 

 of them inhabit the sea coasts of the Antarctic 

 Pole. 



They are more particularly named Petrels, (Procel- 

 larioy) in which the lower mandible is truncated. 



