BIRDS. 



345 



FIG. 337. Restoration of Hesperornis, after Marsh. 



ORDER IV. EURHIPIDUR^E. 



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 dromaeognathous 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/E, containing 

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

 The South American RHEioyE, which have three toes, contain the nandu, 



