NOTES ON THE CANIDH OF THE WHITE RIVER OLIGOCENE. 351 
rated by a wider notch than in Canis. The depression, or fossa, external to the condyle 
is very much deeper and more conspicuous than in the modern genus, in consequence of 
which the condyles project more prominently backward from the occiput than in the 
modern dogs. ‘The paroccipital processes are short, but quite stout and bluntly pointed ; 
they project much more strongly backward and less downward than in the liying forms, 
and are less compressed laterally. Another difference from the modern genus consists in 
the fact that, while in the latter the paroccipital process has quite an extensive sutural 
contact with the tympanic bulla, in Daphenus there is no such contact, the minute bulla 
being widely separated from the process. The direction taken by the paroccipital process 
in its course is thus evidently not determined by the size of the bulla, for in the John 
Day genera, Temnocyon, Hypotemnodon and Cynodesmus, in which the tympanic is greatly 
inflated, the shape and direction of the paroccipital are the same as in Daphenus, with 
its insignificant bulla. A considerable portion of the mastoid is exposed on the surface 
of the skull, but it is rather lateral than posterior in position, a difference from Canis, in 
which the mastoid is hardly visible when the skull is viewed from the side. The mastoid 
process is slightly larger than in the existing genus and is channeled on the inner side 
by a groove leading to the stylo-mastoid foramen. 
The limits of the dasisphenoid are not clearly shown in any of the specimens, but 
this element appears to have much the same broad and flattened form as in the recent 
dogs. The presphenoid is long and narrow and, as in the existing species, is almost 
concealed from yiew by the close approximation of the palatines and pterygoids along the 
median line. The ali- and orbito-sphenoids are not well displayed in any of the speci- 
mens, but so far as they are preserved, they differ little from those seen in the more 
modern members of the family. 
The auditory bulla of Daphenus is very remarkable and differs from that of any 
other known carnivore. Its principal peculiarities were obseryed and noted by Leidy, but 
the material at his command was insufficient to enable him to describe these peculiarities 
with confidence. The tympanic is exceedingly small, and is but slightly inflated into an 
inconspicuous bulla, the anterior third of which is quite flat and narrows forward to a 
point. There is no tubular auditory meatus, the external opening into the bulla being a 
mere hole, but the anterior lip of this opening is drawn out into a short process, some- 
what as in existing dogs. Behind the bulla is a large reniform vacuity or fossa, of which 
Leidy remarks: “ At first, it appeared to me as if this fossa had been enclosed with an 
auditory bulla and what I have described as the latter was a peculiarly modified auditory 
process” (769, p. 33). Several specimens representing both the White River and John 
Day species of Daphenus show that the fossa is normal and was either not enclosed in 
bone, or, what seems less probable, that the bony capsule was so loosely attached that it 
