66 THE STORY OF THE BIRDS 



in their habitat, the three last named being least 

 so. The birds in this order are characterised 

 by the peculiar structure of the feet, the interior 

 toes as well as the hallux or hind toe (which is 

 turned forwards) all being connected by a web. 

 The birds in the various groups (or perhaps 

 sub-orders) vary considerably in structure and 

 appearance. Thus in the Tropic Birds and 

 Frigate Birds the head is large and the neck is 

 comparatively short and stout. In the Cor- 

 morants and Darters the head is small, but the 

 neck is long, especially so in the last-named 

 birds. The Pelicans are furnished with a large 

 pouch between the angle of the lower jaw. The 

 bill is long, straight, and usually compressed, 

 cone-shaped and pointed in the Gannets and 

 Tropic Birds, terminating in a more or less stout 

 hooked nail in the Cormorants and Frigate 

 Birds ; in the Darters, long, slender, and pointed. 

 The legs are placed far back. The wings are 

 long and ample (least so in the Cormorants), as 

 might naturally be expected in such an assem- 

 blage of aerial species. In many species the face 

 and gular region are bare, the latter often furnished 

 with a sac. The tail varies considerably, from 

 the soft rectrices of the Pelicans to the rigid ones 

 of the Cormorants and Darters. In the Tropic 



