FOSSIL VERTEBRA TES—AVES S819 
forms from the Niobrara Cretaceous of Kansas. These were 
described by Marsh and called by him the Odontornithes, he dis- 
tinguished two orders, the Odontolce and the Odontorme (Icthyor- 
nithes) . 
Odontolce: large, flightless, swimming and diving birds that 
resemble the modern diving birds, Loons, etc., in many respects, 
and the Ratite birds in others. The front limbs are almost 
entirely atrophied, the humerus being represented by a slender 
stylet of bone; the skull was elongate and the jaws were fur- 
nished with many sharp teeth that were set in a common groove 
for each jaw. 
Hesperornis, the most typical genus, was a large form about 
three feet high. A similar form Ezalornis is indicated by remains 
from the Greensand of Cambridge, in England, but the structure 
of the anterior limbs is as yet unknown. 
Odontorme (Icthyornithes): much smaller birds than the 
former with well developed wings; the jaws were long, as in 
the preceding genus and were provided with teeth that were set 
in individual sockets; the vertebree were peculiar in that the 
faces, both anterior and posterior, were deeply concave. The 
bird was much like the modern Tern in external characters. 
Icthyornis is the only well-known genus from the Niobrara 
Cretaceous of Kansas. 
The modern birds have many representatives among the 
fossil forms of the late Tertiary, among the most interesting of 
these are’: 
Gastornis,a large flightless bird from the lower Eocene of 
the western part of Europe. It was peculiar in that the bones 
of the skull remained separate instead of forming the usual solid 
brain case. 
Apatornis, Diaphaptoryx, and Aphanapteryx from New Zealand, 
the Chatham Islands, and Mauritius respectively were gigantic 
rails that greatly resembled certain of the living rails. 
Phororachos was an enormous raptorial bird whose remains 
are found in the Tertiary of Patagonia. 
The Dodo (Didus) and the Solitaire from the islands of 
