404 O. C. Marsh—Odontornithes, or Birds with Teeth. 
The scapular arch and the bones of the wings and legs all 
conform closely to the true avian type. The sternum has a 
prominent keel, and elongated grooves for the expanded cora- 
eoids. The wings were very large in proportion to the legs, 
and the humerus had an extended radial crest. The metacar- 
pals are coéssified, as in recent birds, thus differing widely from 
those of Archeopteryx. The bones of the posterior extremities 
are slender, and resemble those of some aquatic birds. The 
centra of the vertebrae are all biconcave, the concavities at 
each end being distinct, and nearly equal. (Plate IX, figures 
3 and 4.) The sacrum is elongated, and made up of a large 
number of codssified vertebre. Whether the tail was elongated 
or not cannot at present be decided. 
The jaws and teeth of this species show it to have been 
carnivorous, and it was probably aquatic. Its powerful wings 
indicate that it was capable of prolonged flight. : 
Another Cretaceous bird, (Apatornis celer Marsh,) belonging 
apparently to the same order as [chthyornis, was found by the 
writer in 1872 in the same geological horizon in Kansas. 
The remains preserved indicate an individual about the same 
size as Ichthyornis dispar, but of more slender proportions. The 
vertebre are biconcave, and thére were probably teeth. _ 
The most interesting bird with teeth yet discovered is per 
haps Hesperornis regalis, a gigantic diver, also from the Creta- 
ceous of Kansas, and discovered by the writer in 1870. The 
type specimen, which was found by the writer in 1871, and 
described soon after, consisted mainly of vertebra and the 
nearly complete posterior limbs, all in excellent preservation.t 
A nearly perfect skeleton of this species was obtained 
estern Kansas by Mr. T. H. Russell and the writer in Novem- 
ber, 1872, during the explorations of the Yale College party, 
and several other less perfect specimens have since been secured, 
and are now in the Yale Museum. These various remains 
apparently all belong to one species. 
The skull of Hesperornis has the same general form as. that 
in Colymbus torquatus Briin., but there is a more prominent 
median crest between the orbits, and the beak is less pointed. 
slight projections from the sides of the grooves. (Plate x, 
figure 2.) The teeth have pointed crowns, covered 
: * This Journal, v, 74, Jan., 1873. + This Journal, iii, 360, May, 1872. 
