BIRDS. 



345 



FIG. 337- Restoration of Hesperornis, after Marsh. 



ORDER IV. EURHIPIDUR^:. 



Toothless birds with pygostyle and saddle-shaped centra to> 

 the presacral vertebrae. The rami of the lower jaw are firmly 

 united* To this order belong all living and many extinct birds. 



\ 



SUB-ORDER i. DROM^EOGNATHI. 



Eurhipidurine birds with dromasognathous palate ; ischium and ilium-, 

 not united behind ; sternum either ratite or carinate ; wings rudimentary or 

 of no use in flight. 



SECTION I. STRUTHIONES. Large ratite birds with elongate hind 

 legs and neck ; bill broad at base ; mouth deeply split ; toes three or two. 

 Restricted to the southern hemisphere. The STRUTHIONID^:, containing 

 the single species Struthio camelus, the ostrich of Africa, has but two toes. 

 The South American RHEID^:, which have three toes, contain the nandu,. 



