NOTES ON THE CANIDA OF THE WHITE RIVER OLIGOCENE. B95 
prominence and, as in Daphcenus, it carries a subcircular facet for the astragalus ; in the 
modern genus this surface is narrower and more elongate. The sustentaculum also agrees 
with that of Daphenus in not being so obliquely placed, with reference to the long axis 
of the caleaneum, as in the existing members of the family. On the plantar side, 
between the sustentaculum and the body of the bone, is a groove, the sulcus flexoris hal- 
lucis, which is better marked in Canis than in either of the White River genera. This 
is curious, in view of the fact that the latter possess. a well-developed and functional 
hallux, while in the former this digit is reduced to the merest rudiment. In Canis we 
find a third facet for the astragalus, a small plane surface distal to the sustentaculum, 
from which it is separated by a narrow sulcus; continuous with this accessory facet, but 
at right angles to it, is a small facet for the navicular. Neither of these articular surfaces 
is to be found in Cynodictis. The facet for the cuboid, which in the recent dogs is almost 
plane and semicircular in shape, is quite deeply concave and of nearly circular outline. 
The cuboid is relatively high and narrow, differing from that of Canis principally 
in the smallness of its transverse and dorso-plantar diameters. The proximal surface is 
occupied by a large facet for the calcaneum, which, as in Daphenus, is much more con- 
vex than in the existing dogs. The hook-like projection from the plantar side, which in 
Daphenus is very large and prominent and in Canis is even more massive, in the present 
genus is quite inconspicuous and is continuous with the projection from the fibular side 
which overhangs the deep tendinal suleus. The astragalar facet is small and is confined 
to the dorsal side of the cuboid, being much less extensive than in Daphenus. ‘The facet 
for the nayicular is not so prominent as in Canis or eyen as in Daphenus, and is con- 
tinuous with that for the ectocuneiform. The distal end of the cuboid resembles that of 
Daphenus in haying quite a concave facet for the head of the fourth metatarsal, while 
that for the fifth is lateral in position. In Canis, on the other hand, the surface for mt. 
ly is almost plane and that for mt. vy occupies an entirely distal position ; the plantar 
portion of the facet for mt. iv is much narrower than in the two White River genera, 
and has thus quite a different shape and appearance. 
The navicular. is almost a miniature copy of that of Daphenus and presents the 
same differences from that of Canis. Seen from the proximal end, it is of more regularly 
oval shape and is less contracted on the plantar side than in the modern genus. The 
position of the navicular in the tarsus is likewise different. In Canis this bone has been 
somewhat rotated, so that its principal diameter is the dorgo-plantar one, and on the 
plantar border it has been brought into contact with the calcaneum, for which it has 
acquired a special facet. It is of interest to observe that a similar but more extensive 
rotation of the tarsal elements has been carried out in the horses, as Riitimeyer has 
shown. In the White River genera, on the other hand, the principal diameter of the 
