ccxii Extinct Birds. BIRDS. Extinct Birds. 
legs, and there are several features of the posterior ex- 
tremities pointing to probable aquatic habits. The 
concavities at each end of the vertebrae are equal and 
quite distinct. Its powerful wings and its formid- 
able teeth would seem to clearly indicate a creature 
capable of prolonged flight, and one of a carnivorous 
nature. In the same geological horizon, in Kansas 
(1872), Prof. Marsh found another form, which he 
calls Apatornis celer. This is regarded as belonging 
to the same order as Ictliyornis. The remains indi- 
cate a bird about the same size as the Ictliyornis 
dispar, but more slender in proportions. 'I’he verte- 
brae are bi-concave, and teeth were probably present. 
'I’lie most interesting specimen discovered is the 
Hesperornis regalis. It is like a gigantic diver, and 
was discovered by Prof. Marsh in the cretaceous of 
Kansas, in 1870. 'I’his bird has a head much like 
that of the Great Diver, G’olymbus. 'I’he peculiar 
features are a stout or prominent median crest be- 
tween the orbits, small brain cavity, and the maxil- 
laiies massive, with a deep inferior groove, thickly 
set with sharp-pointed teeth. There are no true 
sockets, but imperfect projections from the sides of 
the grooves. “'I'he teeth have pointed crowns, cov- 
ered with enamel, and supported on stout fangs. 
* * * In form of crown and base they most 
resemble the teeth of morasauroid reptiles. * * 
The external appearance of the premaxillaries seems 
to indicate that these bones were covered with a 
horny bill, as in modern birds. * * The ster- 
num is thin and weak, and entirely without a keel — 
resembling that of the Apteryx in front. The wings 
are rudimentaiy. The vertebrae of the cervical and 
dorsal regions are of the true ornithic type, the artic- 
ular faces of the centra being quite as in modern 
birds. * * * 'J'lie caudal vertebrm are very 
peculiar, and indicate a structure not before seen in 
birds. * * * 'I’lie pelvic bones, although 
avian in type, are peculiar, and present some well- 
marked reptilian features. * * The acetabu- 
lum differs from that in all known birds, in being- 
closed internally by bone, except a foramen that 
perforates the inner wall.” The remarkable features 
of Hesperornis entitle it, says Prof. Marsh, to be 
placed in the new sub-class, Odontornithes ; but the 
absence of the bi-concave vertebrae, the different 
setting of the teeth upon the jaw, and the absence 
of a keel upon the sternum, place it in a distinct 
order. This order is named Odontolcce. 
Prof. Marsh arranges the group as follows : 
ODON'l'ORNri’HES. 
Birds with Teeth. 
An extinct group, or sub-class, known only through 
certain well-preserved bones, found in the cretaceous 
deposits of Kansas. 
ODON'rOTORMiE. 
Teeth contained in sockets. The vertebrie with 
concave faces on the body, before and behind. 
Sternum with a keel. The wings well developed. 
T’wo genera only are known — Ictliyornis and Apa- 
tornis. 
ODONTOLG^. 
Teeth arranged in grooves. Vertebrae as in recent 
birds. Sternum has no keel. T'he wings rudimen- 
tary. Genus, Hesperornis. 
In Am. Jour, of Sai. and Arts (June, 1876), Prof. 
Marsh records accounts of two additional forms from 
the Kansas cretaceous. They are of “ gigantic size, 
clearly belonging to the Hesperornithidm, although 
quite distinct from Hesperornis regalis, the type of 
the group.” One specimen is enumerated as Lestor- 
nis crassipes, genus and species extinct. The greater 
part of the skeleton is preserved, and it represents a 
bird fully six feet in length. A second species of 
Hesperornis (H. gracilis) is described as being some- 
what smaller than the H. regalis. Another form is 
a species of Ictliyornis (I. victor) about one-third 
larger than the I. dispar. 
