NOTES ON THE CANID.E OF THE WHITE EIVEE 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 Daphcemts. 



The premolars increase in size posteriorly ; in the unworn condition they have high, 

 compressed, thin and very acute crowns, but in old individuals, without showing 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 Daphcenus. 

 The second premolar is much larger than pi; 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- Daphcenus. 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 Cams) 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 Daphcenus. 



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 Cards. The 

 ccnules 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 even 

 in Daphce?ius 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 Daphcenus, 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 Dapha- 



