CHORDATA 34 ! 



Order 3. Crypturi 



The Crypturi (Gr. KpvTrro?, hidden, and ovpd, tail) have a keel 

 on the sternum and the wings are sufficiently well developed to 

 admit of short flights. There are about fifty species living in 

 Central and South America. They are all about the size of the 

 domestic fowl, or smaller ; the tinamou, Tinamus, is one of the 

 most common. 



SUBCLASS II. IMPENNES 



The Impennes (Lat. in, without, and penna, wing) are aquatic 

 birds ; the wings are paddle-like and used only for swimming ; 

 they are commonly called penguins (Fig. 338). In these birds 

 the feathers are uniformly distributed over the whole integu- 

 ment and not confined to special tracts as in most other birds. 

 Beneath the skin is a thick layer of fat, which assists in main- 

 taining the temperature of the body, for the penguins live only 

 in the colder regions of the southern hemisphere, and never on 

 the mainland, but always on rocky and barren islands. They 

 are expert swimmers, feeding on fishes and other marine ani- 

 mals, and when on shore stand erect, side by side, in large 

 "schools." The largest species, the king penguin, is about a 



meter high. 



SUBCLASS III. EUORINTHES 



The Euorinthes (Gr. ev, well, and opvis, bird) include all the 

 remaining birds ; they have the wings well developed and 

 adapted to longer or shorter flights. The feathers are arranged 

 on definite feather tracts, and the sternum bears a keel. The 

 following division into orders is based on differences in the 

 arrangement of the bones which form the roof of the mouth, 

 the details of which need not concern us here. 



Order 1. Desmognathae 

 (Gr. Secr/Ao'?, a band, and yvdOos, jaw) 



Suborder 1. Steganopodes 



The Steganopodes (Gr. areyavoTrov^, web-footed) have webbed 

 feet and are good flyers ; they include the boatswain birds, the 



