NOTES ON THE CANIDEH OF THE WHITE RIVER OLIGOCENE. 365 
pressed laterally. The tooth is relatively smaller than in the recent dogs and thinner 
transversely, and has therefore quite different proportions from those seen in Daphenus. 
The premolars increase in size posteriorly ; in the unworn condition they have high, 
compressed, thin and very acute crowns, but in old individuals, without showmg much 
appearance of wear, these teeth have low crowns, elongated in the fore-and-aft direction. 
The first premolar is very small and simple; it is inserted by a single fang and follows 
immediately behind the canine, without a diastema, which is a difference from Daphenus. 
The second premolar is much larger than p+; it is implanted by two fangs and has a 
perfectly simple crown, without posterior basal tubercle, though the cingulum is thick- 
ened at that point. The third premolar is still larger, especially in the vertical height 
of the crown, and is distinguished by the presence of a posterior tubercle in addition to 
the thickening of the cingulum already found in p 2. The fourth premolar is a very 
effectively constructed, though small, sectorial blade, being much more compressed and 
trenchant than in Daphenus. The anterior cusp of the shearing blade (protocone) is 
relatively higher and thinner and has a sharper point and edge than in the latter genus, 
and the posterior cutting ridge (tritocone) is better developed and more efficient. On 
the other hand, the internal cusp (deuterocone) is very much smaller (hardly larger 
proportionately than in Canis) and occupies a more posterior position. In the Euro- 
pean species of Cynodictis the deuterocone is not so much reduced and is placed as far 
forward as in Daphenus. 
The first molar is large, particularly in the transverse dimension, and is of subquad- 
rate outline. The outer cusps are high and quite acutely pointed, and the central cusp 
(usually called the protocone) is lower and of crescentic shape, and the internal cusp is 
a broad, crescentic shelf, which occupies about the same position as in Canis. The 
ecnules are very small, but of nearly equal size, a difference from the modern genus, in 
which the metaconule is large, while the protoconule is rudimentary or absent, and eyen 
in Daphenus the posterior conule is much the larger of the two. The cingulum is very 
prominently developed upon the outer side of the tooth and forms a large projection at 
the antero-external angle, as in Daphenus, though not in Canis, a reminiscence of creo- 
dont ancestry. 
In the John Day species, C. geismarianus and C. lemur and still more in C. lati- 
dens, the first upper molar has a much more distinctly quadrate crown, due to the enlarge- 
ment of the metaconule, which has become as large as the central cusp, and to the more 
symmetrical development of the internal cusp (? protocone). In the typical European 
species, C. lacustris, on the contrary, the crown of this tooth retains a more trigonodont 
character. 
The second molar is very small, being relatively much more reduced than in Daphe- 
