64 
GENERAL OBNITHOLOGY. 
well developed, with fused metacarpals, and the sterauin is keeled, the vertebrae present the 
extraordinary primitive character of being biconcave. In Hesperornis the vertebrae are 
saddle-shaped, as usual, but the sternum is flat, as in the existing ostriches, and the wings 
are rudimentary, M^anting metacarpals. Some twenty species of several genera of other 
American Cretaceous Birds have been described by the same author. Remains of Birds 
multiply in the next period, the Tertiary. Those of the Eocene or early Tertiary are largely 
and longest known from discoveries made in the Paris Basin, among them the Gastornis 
Fig. 16. — Restoration of Ichthyornis victor. After Marsh. 
parisiensis, at least as large as an ostrich ; some of these belong to extinct genera, others to 
genera which still flourish ; none are known to have true teeth, or otherwise to be as primitive 
as the reptile-like forms of the Cretaceous. The Miocene or Middle Tertiary has proven 
specially rich in remains of Birds, including some of extinct genera, but in largest proportion 
referable to modern types. Later Tertiary (Pliocene and Post-pliocene) birds are almost all 
of living genera, and some are apparently of living species. Extinct birds coeval with man, 
their bones bearing his marks, are found in various caves. Sub-fossil birds' bones occur in 
shell-heaps (kitchenmiddens) and elsewhere, of course contemporaneous with man, and some 
