286 



University of California. 



[Vol. 3. 



This relation occurs at about the same point in the jaw as in the 

 hyaena, but is farther forward in the dentition, owing to the 

 greater antero-posterior extension of the premolars in the hyaena 

 after the reduction of the molars. 



In a comparison of the molar series with that of the mandible 

 of Hyaenognathus, we find the reduced crushing surface of M- 

 corresponding fairly well to the small low tubercles on the short 

 tolonid of the lower sectorial. The presence of a prominent 

 antero-internal angle on the first upper molar may be due to 

 anterior extension following loss of the metaconid on the inferior 

 sectorial. The reduction of the metacone can be accounted for 

 by the median position of the single anterior tubercle of Mt. 

 Finally, the more than ordinarily sharp upward twist of the 

 posterior molar is suggestive of correspondence to the similar 

 curve in the inferior molar series of Hyaenognathus. 



The resemblances just mentioned, coupled with the fact that 

 the two specimens represent individuals not far from the same 

 size, suggest that we are dealing with forms closely related, if 

 not identical. This identity may not be specific, as the two 

 probably do not belong to the same epoch and show a certain 

 degree of difference in dimensions. The writer inclines to the 

 belief that the two forms are generically identical. He doubts, 

 however, whether it is possible to prove identity in the absence 

 of corresponding parts, as characters might exist in either form 

 without finding expression in the general correspondence discussed 

 above. This specimen is therefore given a provisional generic 

 name by which it may be known until the discovery of associated 

 upper and lower jaws gives definite evidence of its affinities. 



As in the case of the mandible of Hyaenognathus, the form 

 represented by this specimen is so different from any known 

 type that its broader relationships are not clear. While it is 

 recognized as a typical canid, it has no close affinities with any 

 well defined group. As in Hyaenognathus, any resemblance to 

 the Amphicyons which appears in the premolars is practically 

 invalidated by the extreme reduction of the molars. There is 

 here, again, some resemblance to certain of the Aelurodons 

 (A. saevus and A. wheelerianusj in the form of I--, and to a 

 certain extent in the outlines of the upper molars. Among the 



