1916] 



Butterworth: A New Mustelid 



23 



is basin-like and irregularly cuspate around the periphery, with the 

 protoconid, metaconid, hypoeonid, and entoconid faintly defined. 



The unmistakable differences presented by the second lower molar 

 are sufficient to separate the new mustelid from the Procyonidae, the 

 only other phylum of the Carnivora possessing characters close enough 

 to justify comparison. Though there can be no question as to its 

 mustelid affinities, the Thousand Creek form seems markedly different 

 from any other representative of the group. Resembling the modern 

 badgers in its generic characters, specimen 22290 shows the following 

 noteworthy contrasts to the Recent Taxidea taxxis neglecta of North 

 America: (1) The heel of M 1 of the Thousand Creek form is rela- 

 tively larger in every dimension than the heel of this tooth in Taxidea. 

 (2) In Taxidea the tubercles of the heel are much more highly speci- 

 alized for a cutting function. (3) In Taxidea the metaconid is slightly 

 less prominent and is posterior to the protoconid, while the metaconid 

 of the fossil tooth is located nearly as far forward as the protoconid. 

 The general structure of the carnassial is, however, much alike in the 

 two forms, and the structure of the last premolar is identical. 



Fundamental differences exist between the fossil mustelid and 

 Meles. The simple spike-like P 4 of the Old World badger is in marked 

 contrast to the bicuspate P 4 of the form from the Thousand Creek. 

 The former has the cutting shear of the carnassial well developed, the 

 latter exhibits a more primitive structure of this part of the tooth. 

 In Meles the metaconid of M 1 is situated far posterior to the proto- 

 conid and the markedly basin-like heel is cuspate only around the 

 border of the tooth, while the metaconid of the fossil tooth is located 

 almost as far forward as the protoconid, and the heel has no pro- 

 nounced basin. 



Lutra, Lutreola, and Mephitis possess dental characters widely 

 divergent from those of the Thousand Creek mustelid. These char- 

 acters preclude any possibility of close relationship to the form under 

 discussion. 



The fossil form resembles Taxidea in the structure of the lower 

 carnassial and of P 4 , though there occur notable differences of pro- 

 portions. It resembles Meles in the ratio between the heel dimensions 

 and the anterior portion or triangle of the carnassial, but differs from 

 the latter form in the conformation of the heel of this tooth and also 

 in respect to the number of cusps of P 4 . 



It is evident that the Thousand Creek form is more closely related 

 to Taxidea than to Meles, as differences of structure are of higher rank 



