0. C. Marsh—Odontornithes, or Birds with Teeth. 407 
slender, compressed phalanges, which correspond essentially in 
their main features with those of modern Divers. 
The remains preserved of Hesperornis regalis show that this 
species was larger than any known aquatic bird. All the 
specimens discovered are in the Yale College Museum. and 
agree essentially in size, the length from the apex of the bill to 
the end of the toes being between five and six feet. The hab- 
its of this gigantic bird are clearly indicated in the skeleton, 
almost every part of which has now i 
The two orders of birds with teeth would then be distin- 
guished as follows :— 
Sub-Class, ODONTORNITHES (or AVES DENTAT#). 
A. Teeth in sockets. Vertebre biconcave. Sternum with keel. 
Wings well developed. 
Order, IcHTHYORNITHES. 
B, Teeth in grooves. Vertebre as in recent birds. Sternum 
without keel. Wings rudimentary. 
Order, ODONTOLOZ. 
In comparing Ichthyornis and Hesperornis, it will be noticed 
that the Batbiasion of charaseess oh aack is very remarkable, 
and quite the reverse of what would naturally be expected. 
The former has teeth in distinct sockets, with biconcave verte- 
bre; while the latter has teeth in grooves, and yet vertebrae 
similar to those of modern birds. In point of size, and means 
of locomotion, the two present the most marked contrast. The 
fact that two birds, so entirely different, living together during 
the Cretaceous, should have been poorer in such perfect 
Preservation, suggests what we may yet hope to learn of life in 
that period. 
