Vol. 5] 



Kellogg 



, — Rodent Fauna. 



431 



DIPOIDES, sp. probably new. 

 Fig. 14. 



No. 12536, Univ. Calif. Col. Vert, Palae., left 1\ and M 1; from 

 locality no. 1103, Thousand Creek, Humboldt County, Nevada. 



These two teeth, P 4 and M 1; are very like those of Dipoicles 

 problematic us Sehlosser found in the Bohnerzen of Salmandingen 

 and Melchingen. The great difference in the geographic location 

 of the two would seem a reasonable ground for specific separation 

 taken in connection with the fact that the teeth of the American 

 form are larger. 



Measurements. 



No. 12536 D. problematicus 



P 4 , anteroposterior diameter 5.9 mm. 4.8mm. 



Mj, anteroposterior diameter 4.5 4.1 



P 4 , transverse diameter 4.6 4.6 



M„ transverse diameter 4.8 4.2 



ENTOPTYC'HUS MINIMUS, n..sp. 

 Pig. 15. 



Type no. 12569, Univ. Calif. Col. Vert, Palae., portion of left 

 ramus of the lower jaw with P 4 , M 1; M 2 . Locality no. 1103 at 

 Thousand Creek, Humboldt County, Nevada. 



Specific Characters. — Extremely small size. 



Description and Comparison. — The three teeth of this speci- 

 men are practically similar, being prismatic and with a deep fold 

 on the inner side running almost to the outer margin, but the 

 premolar is distinguished by a slight fold on its outer side also. 

 In their half -worn state they show a tendency to form in the 

 center a tube, entirely surrounded by enamel, a condition which 

 is described by Dr. Matthew as being characteristic of this 

 genus. The specimen is very much smaller than any of those of 

 Entoptychus minor from the John Day Beds, although the tooth 

 pattern is quite similar. 



Measurements. 



No. 12C69 



P 4 , anteroposterior diameter 1.0 mm. 



M,, anteroposterior diameter 0.9 



M 2 , anteroposterior diameter 0.9 



P 4 , transverse diameter 1.2 



M 1( transverse diameter 1.2 



Mo, transverse diameter 1.3 



Height of ramus at P 4 : 3.2 



