ANCIENT BIRDS 217 
the end of the toes must have been between five and six feet (see 
Plate XXXIV.). Its habits are clearly indicated by the skeletons 
described by Professor Marsh in his splendid monograph on The 
Extinet Toothed Birds of North America. No living birds possess 
teeth in their jaws, so that the presence of such in Hesperornis 
Fic. 81.—Skeleton of Hesperornis regalis, from Cretaceous strata, North America. 
(After Marsh.) 
and other birds of the Cretaceous period at once separates them 
from those of the present day. It cannot be doubted that this 
antique diver was carnivorous ; it probably devoured fishes. The 
teeth were set in a groove, and old ones were replaced by young 
ones growing up from inside the fang. The breast-bone (sternum) 
was entirely without a keel. The single thin wing-bone (humerus) 
