CHAPTER XX. 



THE TUBE-NOSED BIRDS, DIVING BIRDS, AND PENGUINS, 

 Orders TUBINARES, PYGOPODES, AND IMPENNES. 



WITH the exception that they are all thoroughly aquatic in their habits, the tube- 

 nosed birds, as represented by the albatrosses, petrels, and shearwaters, have little 

 or nothing in common with the diving-birds, as exemplified by the auks, divers, 

 and grebes, or with the penguins; and it is merely as a matter of convenience that the 

 three groups are treated in the same chapter. They accordingly need no collective 

 notice, so that we at once proceed to the consideration of the leading features of 

 the first of the three groups. 



Tube-Nosed The members of this order take their name from the circum- 



Birds. stance that the external nostrils are produced into tubes lying upon 

 the surface of the beak and directed forwards ; this feature being absolutely 

 peculiar, and serving at once to distinguish them from all other birds. 

 The horny sheathing of their beak is composed of several distinct pieces, 

 separated from one another by more or less marked grooves; and the tip of 

 the beak is sharply hooked. In the skull the palate is of the slit (schizognathous) 

 type ; while its nasal apertures are oval, or holorhinal, and the angle of the lower 

 jaw is abruptly truncated behind. As in so many sea-birds, the upper aspect of 

 the skull has very deep grooves, which, however, are always separated from one 

 another on the forehead by a wide bar. The vertebrae of the back are articulated 

 with one another by the usual saddle-shaped surfaces. In the wings, which are 

 generally of great length, the humerus resembles the corresponding bone of 

 the gulls in having a well-marked process on the outer side of its lower extremity, 

 although the perforations in the basal bone of the second digit of the wing 

 characterising that order are wanting. The tibia, or leg-bone, differs from that 

 of all the birds hitherto considered in having a flattened plate-like crest projecting 

 upwards on its front aspect some distance above the level of the head of the bone. 

 The feet are characterised by the small size or even occasional absence of the first 

 toe, while the three front toes are completely webbed. In the plumage there is 

 a well-defined bare tract on each side of the neck, and the oil-gland is furnished 

 with a tuft of feathers. The young, which are born in a helpless condition, and 

 are fed for a considerable period in the nest by the parents, are clothed with down, 

 arranged in a somewhat complex manner. 



In habits, all the tube-nosed birds are marine and carnivorous, subsisting 

 entirely on either carrion, cuttle-fish, or crustaceans, together with such refuse as 

 they can pick up. They are all birds of sustained and powerful flight ; and, with 

 the exception of the members of one aberrant genus, are swimmers rather than 



