KEEL-BREASTED BIRDS. 237 
powerful, and provided with only two toes, the inner one 
being twice as long as the outer. 
VALUE—The oil, skin (leather), and feathers are all used. Os- 
triches are now farmed in this country for their feathers. 
Fic. 277.—Ostrich (Struthto camelus) running at full speed. 
Sub-Class IV.—KEEL-BREASTED Birps (Carinate). 
General Characteristics—All the rest of the birds are 
included in this class. They are distinguished by a keeled 
sternum or breastbone, the fore-limbs in the higher forms 
being developed as organs of flight. 
Order I. Penguins (Sphenisci).—The Penguins (Fig. 
278) are confined to the Antarctic region, and are remark- 
ably fish-like in their habits. The wings are small, and cov- 
ered with scale-like feathers, and are used, as well as their 
webbed feet, as paddles. The king-penguin (Aftenodytes 
longirostris) is one of the largest, attaining a height of three 
