NOTES ON THE CANIDZ OF THE WHITE RIVER OLIGOCENE. 399 
zygomatic process is stout and well-developed, especially in D. vetws, which has heavier 
arches than a large wolf, while in D. hartshornianus the zygoma is lighter and more 
slender, much as in the coyote. The jugal is strongly curved upward, as well as out- 
ward, and is shaped quite as in Canis, forming nearly the whole anterior and inferior 
boundary of the orbit ; the postorbital process is very feebly indicated, being even less 
prominent than in the modern genus, so that the orbit is more widely open behind. The 
lachrymal is rather larger than in Canis, forming more of the anterior orbital border, and 
has a quite well-developed spine. 
The nasals have a general resemblance to those of Canis, but, in correspondence with 
the shortness of the whole facial region, they are considerably shorter, and somewhat 
broader and more conyex transversely ; their posterior ends are more simply rounded and 
have a less irregular suture with the frontals, while the anterior, free ends are much less 
deeply notched. 4 : 
The maxillary is somewhat peculiar in shape, corresponding to the remarkably 
constricted, narrow muzzle. The facial portion of the bone is relatively higher than in 
existing representatives of the family, especially in front, its anterior border rising in a 
steeper and bolder curve. Just in advance of the orbits the maxillaries expand quite 
suddenly in the transyerse direction, much more abruptly than in Canis. The infra- 
orbital foramen occupies nearly the same position, with reference to the teeth, as in the 
latter genus, being above the front edge of the sectorial, but it is very much nearer to 
the orbit, which occupies a more anterior position. The palatine processes of the maxil- 
laries follow the shape of the muzzle, and are long, narrow for most of their length, but 
broadening much behind; anteriorly they are emarginated in an unusual degree to 
receive the long premaxillary spines. 
The premaxillaries, especially their alveolar portion, are somewhat narrower than in 
Canis, and behind the external incisor the alveolar border is constricted on each side, 
forming well-marked grooves for the reception of the lower canines. The exposed part 
of the ascending ramus is much narrower than in the modern genus, forming a mere 
strip on the side of the narial opening. At the same time, this ascending ramus is 
relatively longer than in existing dogs and extends almost to the nasal process of the 
frontal. The anterior narial opening is somewhat larger proportionately than in the 
recent members of the family, especially in the vertical direction, and its borders are less 
inclined ; the floor, formed by the dorsal surface of the horizontal rami of the premaxille, 
is more simply and deeply concave, and the horizontal rami themselves are less massive. 
The palatine processes of the premaxillaries are distinctly smaller than in Canis, while 
the spines are relatively longer and more slender. The incisive foramina are large and 
from them quite deep grooves are continued forward to the alveolar border, while in the 
modern genus these grooves are yery shallow and feebly marked. 
