CREODONTA. 
89 
Bkeleton known. The posterior part of the ramus is not inflected according 
to Gervais, and he therefore does not refer it to the Marsupialia* The 
nearest European representative of Oxycena is Pterodon^ in which the form 
of the mandible also forbids a reference to the Marsupialia^ as Gervais has 
remarked. Both genera are doubtless members of the suborder of Creodonta. 
The genus Hyoinodon, on the other hand, is not referable to the same group, 
since the figure given by Professor Gervais f representing the brain of the 
originally-described type, II. leptorhyncJms of the Miocene period, displays 
characters of the true Carnivora. The anterior part of the cranial cavity of 
the specimen moulded is broken away. 
It is possible that the genus Diacodon, Cope, belongs here also ; its spe¬ 
cies resemble slightly the Cliiroptera in the inferior dentition, and are of 
small size. Here must also l)e referred supposed Carnivora from the Eocene 
of Wyoming, stated by Marsh to be allied to the Viverrida\ 
The genus Mesonyx,X which I discovered in the Bridger beds of Wyo¬ 
ming, cannot be referred to the Creodonta as here constituted, since the 
trochlear face of its astragalus is completely grooved above as in the true 
Carnivora^ and its distal end presents two distinct facets, one for the cuboid, 
and the other for the navicular bones. It represents on this account a pecu¬ 
liar family, the Mesonychidce. 
There are various degrees of development of the sectorial structure of 
the molars in this suborder. In some of them, as Didyniictis, only one of 
the inferior molars presents this structure; in others two, and in others 
three. In one type, the last superior molar is longitudinal; in others, it is 
transverse. In Arctocyon, the superior true molars are tubercular. ' For the 
2 )resent I point out the three following families as well defined : 
. 1. AmloloctonidcE. —Last sujDerior molar longitudinal; inferior molars 
with the internal tubercle little developed. Genera,— Amhloctonus, and per¬ 
haps Palceonyctis. 
2. Oxyoenidoe. —Last superior molar transverse ; the preceding ones sec¬ 
torial; inferior molars sectorial. Genera,— Stypoloplms, Oxyana.^ Pterodon^ 
and perhaps Patriofelis. 
*Nouv. archives chi museum, 1870, 151. 
t Loc. cit., pi. vi, fig. 5. 
I Ann. Kept. U. S. Geol. !3urv. Terrs., 1873, p. 550. 
