CLASS AVES 589 



Order 2. Ichthyornithiformes. — Fossil, toothed-birds from 

 America, with teeth set in separate sockets. Example: Ich- 

 thyornis (Fig. 479). 



Order 3. Struthioniformes. — Ostriches. — Flightless, ter- 

 restrial birds with naked head, neck, and legs; feet with two 

 toes; without pygostyle; no keel on sternum. Example: 

 Struthio, African Ostrich (Fig. 480). 



Order 4. Rheiformes. — Rheas. — Flightless, terrestrial birds 

 with partially feathered head and neck; feathers without after- 

 shaft; feet with three toes. Example: Rhea, American Ostrich 

 (Fig. 481). 



Order 5. Casuariiformes. — Cassowaries and Emeus. — 

 Flightless terrestrial birds with very small wings; feathers with 

 large aftershaft. Examples: Casuarius, Cassowary; Dromcens, 

 Emeu (Fig. 482). 



Order 6. Crypturiformes. — Tinamous. — Flying, terrestrial 

 birds, with short tail; no pygostyle. Example: Tinamus (Fig. 



483)- 



Order 7. Dinornithiformes. — Moas. — Flightless, terrestrial 

 birds, with enormous hind limbs; wing bones absent ; all extinct. 

 Example: Dinornis (Fig. 484). 



Order 8. .52pyornithif ormes. — Elephant-birds. — Flightless, 

 terrestrial birds, with enormous hind limbs; sternum and wings 

 small; eggs very large ; all extinct. Example: JEpyomis. 



Order 9. Apterygiformes. — Kiwis. — Flightless terrestrial 

 birds; feathers hair-like and without aftershaft; all small in 

 size. Example: Apteryx (Fig. 485). 



Order 10. Spheniscif ormes. — Penguins. — Flightless marine 

 birds, with small, scale-like feathers ; wings modified as 

 paddles for swimming; one family. Example: Spheniscus 

 (Fig. 486). 



Order n. Colymbif ormes. — Loons and Grebes. — Aquatic 

 birds with webbed or lobed toes; feet far back; body carried 

 upright; two suborders and two families. Examples: Gavia, 

 Loon (Fig. 487); Dytes, Grebe. 



