NOTES ON THE CANIDA OF THE WHITE RIVER OLIGOCENE. 327 
transversely and antero-posteriorly than in most recent species of Canis. As in that 
genus, the external incisor is much the largest tooth of the series, and forms with the 
upper and lower canines a formidable lacerating apparatus. The diastema between the 
incisors and the canine is somewhat greater than in Canis, and the premaxillary is quite 
deeply constricted at that point, forming a groove for the reception of the lower canine. 
The canine is of the usual compressed, oval section, but the compression is less 
decided than in Canis, the longitudinal diameter not so greatly exceeding the transverse. 
The fang of the canine is long and stout, producing a marked swelling upon the outer 
face of the maxillary ; the crown is of only moderate length, but is both actually and 
proportionately heavier than in the coyote (C. latrans). 
The premolars are notably small and simple; they increase in size regularly from 
the first to the fourth, the sectorial being, of course, much larger than any of the others. 
The first premolar is implanted by a single fang, and has a small crown of compressed 
conical shape, with much less conspicuous internal cingulum than in the recent species of 
the Canide. 'The second premolar is decidedly smaller than in most of the modern dogs, 
and is separated by longer interspaces from both the preceding and the succeeding tooth ; 
it has a low, pointed, simple and much compressed crown, without the small posterior 
tubercles which are found in nearly all the recent species of the family. The third pre- 
molar is much longer and especially has a higher crown than p 2, but has a similar shape, 
without posterior basal tubercles, and, like p 2, is inserted by two fangs. The sectorial (p + 
is very primitive in character, as compared with that of the typical recent species of 
Canis. Certain modern members of the family, such as Ofocyon and Canis corsac, for 
example, have, it is true, even smaller and simpler sectorials than Daphenus, but as in 
these forms this is doubtless due to a secondary simplification, they need not be drawn 
into comparison. The primitive character of the sectorial in the White River genus is 
shown in the thick, pyramidal shape of the antero-external cusp (protocone) which is less 
compressed and trenchant than in the modern species, in the smaller size of the postero- 
external cutting ridge (¢r7tocone) and in the unreduced internal cusp (dewterocone) which 
is very much larger and more prominent than in Canis, and is carried upon a larger 
fang. The position of this inner cusp with reference to the protocone is the same as in 
the recent genus. As a whole, the sectorial is small and gives to the dentition a decidedly 
microdont character. 
The premolar series of the two sides diverge quite rapidly posteriorly, each tooth, 
except p 1, being oblique in position, with reference to the long axis of the skull, thus 
giving the bony palate its greatest width at the hinder edge of the sectorials. The 
obliquity of the teeth and their divergence posteriorly are eyen more strongly marked 
than in most recent dogs. 
A, B §& VO, SIOX, Y P, 
