VERTEBRATA. 



259 



ers ; the great quill tail feathers, so useful in steering 

 are the rectrices ; those lying over the humerus and 

 scapular are the scapulars; the proximal end of the 

 ulna is covered with the tertiarics ; the distal end of the 

 same bone with the secondaries ; while the bones of the 

 hand support the primaries, which are largest of all. 

 Each quill often carries a little light feather just beneath 

 the commencement of the vane, the accessory plume, or 

 plumule. These form the greater, lesser, and under 

 wing coverts. (Fig. 154.) 



Order I. Natatorcs, or Swimmers. These have the 

 body boat-shaped, and the feet more or less webbed. 



One division of swimming birds is called Brevipinnata, 

 (Short-wings,) the feathers and wings being short. It 



FIG. 155. Common Tern. 



includes the Penguins, Grebes, Puffins, Guillemots, and 

 Divers. In the Penguins the wings are too short for 



