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University of California Publications in Geology [Vol. 10 



submission of any but inferential data regarding the teeth anterior 

 to P 4 . 



Judging from the crowding of the entire dentition anteroposteri- 

 orly and the difference in size between the root of P 4 and the alveolus 

 of P.,, it is to be assumed that the premolars of specimen 22290 have 

 suffered reduction in number and dimensions, consisting in part in the 

 elimination of P^ 



P 4 , the sole complete representative of the premolar series, is robust 

 and possesses a cusp posterior and external to the protoconid. This 

 cusp is prominent in the Procyonidae and other carnivore phyla, but 

 seems to reach its highest development in the mustelid genera Maries 

 and Taxidea. 



Fig. 1. Taxidea nevadensis, n. sp. Type specimen, no. 22290, X 2. Outer 

 and occlusal views of lower dentition. Thousand Creek beds, Thousand Creek, 

 Nevada. 



Mi is heavy and possesses a rudimentary shear. The paraconid 

 and protoconid are of equal size, and with the slightly smaller meta- 

 conid form an approximately equilateral triangle. The paraconid is 

 clearly mediad of the median anteroposterior line of the tooth. The 

 heel of M 1 is larger than that observed in any of the described mustelid 

 forms with the exception of Meles, the Old World badger. The heel 

 is somewhat trilobate in form. The hypoconid and entoconid are 

 exceptionally well developed, and the posterior region is elevated to 

 form a horseshoe-shaped ridge. 



M 2 is nearly circular in cross-section, and probably single-rooted. 

 It is inserted at an angle of about 15° to the occlusal surface of the 

 heel of the carnassial, bringing its crushing face mediad of the median 

 anteroposterior line of the dentition. This character is possibly at- 

 tributable to individual variation. The crushing surface of the tooth 



