Vol. 5] 



Kellogg 



. — Rodent Fauna. 



427 



Measurements 



P.,, anteroposterior diameter 



P 4 , transverse diameter of anterior portion . 



P 4 , transverse diameter of anterior ridge 



Incisor, transverse diameter 



Incisor, anteroposterior diameter 



A comparison with A. monax shows that A. minor has a more 

 decided ridge on the anterior face of P 4 , the metaconid is higher 

 and the protoconid and hypoconid farther apart, the heel of the 

 tooth is not so low, and none of the lower teeth slope downward 

 on the inner side. The incisors and P 4 are large in proportion 

 to the other teeth. M 2 and M 3 are set straight in the jaw and 

 not sloped downward and outward. 



A. minor differs from Palaearctomys macrorhinus in having 

 smaller incisors and a larger M 3 , with two ridges instead of one. 

 M- has three ridges instead of two. The incisors lack the longi- 

 tudinal furrows given as a generic character of Palaearctomys. 



Measurements. 



A. tn inor P. macrorhinus 



Anteroposterior diameter of larger incisor 4.2mm. 



Anteroposterior diameter of smaller incisor 4.1 7.0 nun. 



Transverse diameter of larger incisor 3.3 5.0 



Transverse diameter of smaller incisor 2.7 



M 1 , anteroposterior diameter 4.3 4.2 



M 2 , anteroposterior diameter 3.4 3.5 



M s , anteroposterior diameter 4.2 3.7 



M', transverse diameter 3.3 3.4 



M 2 , transverse diameter 4.1 4.0 



M 3 , transverse diameter 4.1 3.5 



CITELLUS, sp. 

 Fig. 8. 



No. 12570, Univ. Calif. Col. Vert. Palae., a worn M x from 

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



This tooth does not exhibit any specific characters distinguish- 

 ing it from Callospermophilus trepidus, a new species obtained 



No. 12538 No. 3079 2 



4.2 mm. 4.8 mm. 



3.4 3.7 



1.1 2.2 



2.7 3.0 



4.1 4.2 



- Calif. Mns. Vert. Zool. 



