258 Marsh's Monograph on the Odontornithes 
preservation of the fragile bones here described is due. 
strata containing them correspond to what has been called 
Marsh the “ Pteranodon beds,” a part of Meek and Hay- 
den’s Cretaceous Number 3. This horizon is extremely rich in 
vertebrate fossils, and contains many fishes, Mosasauroid rep- 
tiles, Plesiosaurs and Pterodactyles. 
The first specimen of Odontornithes found was the distal end 
of a tibia collected by Professor Marsh in 1870. Other por- 
tions of the skeleton were soon afterward brought to light, and 
among which are several almost complete skeletons of Hesper- 
ornis and rich material of Zchthyornis. 
“A study of this extensive series of Bird remains brings to 
nithes. One of these groups includes very large ; 
birds, without wings, and with the teeth in grooves (Odontolce); 
represented by the genus Hesperornis contain 
class, now a closed 
the d 
them. 
Hesperornis, the type of the order Odontolewe, was an aquatie 
bird of great size, measuring almost six feet from the tip of the 
bill to the end of the toes. Owing to the completeness of the 
remains, its affinities and probable habits have been very fully 
and clearly made out. th 
The teeth had conical pointed crowns covered with smooth — 
enamel and somewhat directed backward, and their fangs Wet? — 
; ype; ce they are well worth of 
etailed description and full illustration here devot to 
