64 



GENEBAL ORNITHOLOGY. 



well developed, with fused metacarpals, and the sternuin is keeled, the vertebrae present the 

 extraordinary primitive character of being biconcave. In Hesperornis the vertebrse are 

 saddle-shaped, as usual, but the sternum is flat, as in the existing ostriches, and the wings 

 are rudimentary, wanting 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 Ichthtjornis victor. After Marsh. 



parisiensis, at least as large as an ostrich ; some of these belong to extinct genera, others to 

 genera which stDl 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 (kitclieumiddens) and elsewhere, of course contemporaneous with man, and some 



