II NEORNITHES ODONTOLCAE 45 
thidae ; while the nostrils are pervious, and the quadrate articu- 
lates with the skull by two heads, contrary to what occurs in the 
Ratitae proper. The furcula is existent, but extremely slender ; 
the metatarsus is more or less elongated, the hallux is present, 
the wings are small but well developed, and the tail is said to be 
long, with a considerable number of separate vertebrae. 
This genus includes the species P. longissimus, P. inflatus, P. 
platygnathus, P. modicus, P. gracilis, and P. sehuensis ; Brontornis, 
which has a shorter and wider mandible and smaller but stouter 
metatarsi, possesses In b. burmeisteri a form as large as Aepyornis 
maximus, While Opisthodactylus and other proposed genera are too 
imperfectly known to deserve consideration in our limited space. 
Besides the above, Dr. Gadow classed with the Stereornithes, 
Diatryma of New Mexico, known from a metatarsus ; Dasornis of 
the London Clay, described from fragments of a skull; Remiornis 
from the neighbourhood of Rheims, of which several imperfect 
bones have been found ; and Gastornis of both England and France, 
of which a fair number of parts have been unearthed. All occur 
in the Kocene, but the question of their relationship is by no. 
means settled, and some writers consider Gastornis to be nearly 
allied to the Anseres. This form appears to have been of the size 
of an Ostrich, with long leg-bones and short weak wings, and 
was probably flightless. Three species have been propounded, 
G. parisiensis, G. klaasseni, and G. edwardsi. 
(B) With regard to the difficult question of the position in the 
system of the Neornithes Odontolcae, a few introductory words 
of explanation are necessary. In 1872 Professor Marsh bestowed 
upon two fossils from the Cretaceous deposits of Kansas the 
names of Hesperornis and Ichthyornis, which he proposed in the 
following year’ to comprise in a Sub-class Odontornithes, so called 
from the presence of teeth in the jaws. Subsequently ~ he divided 
this Sub-class into two Orders, Odontoleae and Odontotormae, the 
former containing Hesperornis, with the teeth arranged in grooves, 
and the latter Jchthyornis, where they were placed in distinct 
sockets. His views have been controverted by many writers, 
but Mr. Lydekker—an authority of great weight in this con- 
nexion—while fully admitting the affinity of the first form to 
ie 
1 Amer. J. Sci. (8) v. 1873, pp. 161, 162. 2 Op. cit. x. 1875, pp. 403-408. 
