3 
the sarcophagous Marsupialia or to the Insectivora. It has, how- 
ever, decided resemblances in the form of the molars, and in the | 
deficiency i in the number of the inferior incisors, to such genera 
of Insectivora as Mythomys and Solenodon, while in the large 
canines, it more nearly approaches Sarcophaga and Carnivora. 
I propose to include the genera Ambloctonus, Oxyxna, Stypolo- 
phus, and Didymictis in a special division under the name of 
Creodonta. This division may be regarded as a suborder of the > 
Insectivora. Itis possible that the genus Diacodon Cope belongs 
here also; its species resemble Chiroptera in the inferior dentition, 
and are of small size. The genus Mesonyx,' which I discovered ' 
in the Bridger beds of Wyoming, cannot be referred to the Creo-~ 
donta as here constituted, since the trochlear face of the 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 
peculiar family, the Mesonychide. 
To the Creodonta must be referred the genera Pterodon and. 
Palzonictis of De Blainville, from the French Eocene. This 
author and Pomel placed them in the Marsupialia, but Professor : 
Gervais remarks (Geologie et Paleontologie Frangaise) that the 
evidence is insufficient for such a course. Here also doubtless 
belong supposed Carnivora from the Wyoming Eocene, stated by 
Marsh to be allied to the Viverride. 
The remarkable type first introduced to the notice of. paleonto- 
logists by Leidy, represented by the genera Anchippodus, Ecto- 
ganus, etc., has been looked upon as an order of Mammalia ‘by 
Marsh, and termed the Tillodontia. He gives,’ as its characters, 
the possession of claws, plantigrade feet with five toes, a third 
trochanter of the femur, and separate scaphoid and lunar bones. | 
Also, that the dentition is characterized by “ molars of the ungu- 
late type,” small canines, and large scalpriform incisors in both 
jaws, faced with enamel and growing from persistent pulps as in 
the Rodentia. He says this order “seems to combine characters 
of the orders of carnivores, ungulates, and rodents.” 
Except in the dentition, the definition above given applies to 
the Creodonta; and an analysis of the dentition shows so many 
points of resemblance as to render it ‘probable that they pertain 
to the same order of Mammalia. Also, except in the dentition, 
the characters given by Prof. Marsh do not differ from those of 
the Insectivora. The structure of the superior molars is not in- 
consistent with the same order, and the small canines and large 
incisors are even more like those of most Insectivora than are 
Creodonta. The singular form of these incisors, and their growth 
from persistent pulps, is rather characteristic of Rodentia. The 
transverse or tubercular premolars also distinguish this group 
from both the Creodonta and the true Insectivora. The defini- 
tions of the order and sub-orders will then be as follows :— 
1 Ann, Rept. U. 8. Geol. Surv.. Terrs., 1872, p. 550. 
2 Amer. Journ. Sci. Arts, 1875, 231.. - - 
