BIRDS. 



345 



FIG. 337. Restoration of Hesperornis, after Marsh. 



ORDER IV. EURHIPIDUR^:. 



Toothless birds with pygostyle and saddle-shaped centra to 

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

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



SUB-ORDER 



D ROM^EOGN ATH I. 



Eurhipidurine birds with dromaeognathous palate ; ischium and ilium 

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



use in flight. 



Si.c nox I. STRUTHIONES. Large ratite birds with elongate hind' 



.'I neck; bill broad at base; mouth deeply split ; toes three or two. 



Restricted to the southern hemisphere. The STRUTHIOXID^E, containing 



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



The South American RHEID.-K, which have three toes, contain the nandu, 



