1884.] The Creodonta. 263 
mal from France under the name Afiterodon gaudryi. He has 
not stated how this genus differs from Amblyctonus. 
Fig. 4. Fig. 5. 
Fic. 4.—Part of mandibular ramus of Ambiyctonus sinosus Cope, with the last 
three molars ; upper figure the same, from above; two-thirds nat. size. From the 
Yasatch beds of New Mexico. Fic. 5.—Distal ends of tibia of, a-b, Amblyctonus 
sinosus, and c d e, Oxyena morsitans Cope; 4 and d, distal views; two-thirds natu- 
l size. From the Wasatch beds of New Mexico. Original, from U. S. G. G 
Expl. Surv. W. of tooth mer., G. M. Wheeler. 
In the genus Mesonyx we have a structure of the astragalus 
found only elsewhere in flesh-eating mammals in the Hyznodon.? 
Its distal extremity has two well-marked facets, one for the navic- 
ular bone and one for the cuboid (Fig. 9).. The appearance is 
that of a perissodactyle mammal, and the astragalus of the Me- 
onyx might well be taken for that of an ungulate of that sub- 
order. The tibial face of the bone is grooved, another point in 
which it differs from most of the Creodonta. Still another char- 
acteristic peculiarity is seen in the forms of the ungues. These 
are neither claws nor hoofs, but between the two, resembling the 
corresponding part in some Rodentia. Their deeply fissured ex- 
‘remities show that they are rather allied to claws than to hoofs 
(Fig. 10). The narrow navicular facet of the astragalus renders 
it probable that the inner digit or hallux is wanting, and that 
there are but four toes in the hinder foot. The form of the trape- 
zum shows that there are but four toes on the anterior foot (Fig. 
7). One more character completes the singular ensemble pre- 
sented by this genus. The zygapophy’ses of the lumbar vertebrae 
embrace each other as in the lower perissodactyles and artio- 
les, a character not found in the Carnivora or Insectivora. 
"Fide Professor W. B. Scott. 
