Vol. 5] 



Kellogg 



, — Rodent Fauna. 



433 



Measurements. 



J 



s T o. 12571 



No. 12572 P. 



californicut 



M,, anteroposterior diameter 



2.0 mm. 





1.8 mm. 



Mo, anteroposterior diameter 



1.6 





1.3 



M„ anteroposterior diameter 



1.4 





.9 



M„ transverse diameter 



1.3 





1.1 



Mo, transverse diameter 



1.4 





1.1 



M„ transverse diameter 



1.3 





.8 



Height of ramus over mental foramen.... 



2.4 



2.7 mm. 



2.4 



Height of ramus at M, 



3.7 



3.8 



3.6 



Length of tooth row 



5.6 



5.8 



4.3 



Incisor, transverse diameter 





.8 



.6 



Incisor, anteroposterior diameter 





1.3 



1.1 



PEKOMYSCUS f, sp. 



No. 12573 and no. 12574, portions of two rami of lower jaws 

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

 Nevada, without teeth but so small as to make them evidently 

 specifically different, although no very accurate conclusions can 

 be drawn without the teeth. 



Measurements. 



No. 12573 No. 12574 



Length of tooth row 3.7 mm. 3.8 mm. 



Height of ramus over mental foramen 2.0 1.8 



Height of ramus at M, 2.9 2.8 



DIPKIONOMYS PARVUS, n. gen. and sp. 

 Figs. 1 7(i, 17 b. 



Type no. 12566, Univ. Calif. Col. Vert. Palae., anterior por- 

 tion of a right ramus of the lower jaw with incisor, P 4 , M,. The 

 beginning of the angle and coronoid process are indicated, but 

 the rest of the posterior portion of the ramus is lacking. From 

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



Generic and Specific Characters. — The angle of the ramus 

 does not turn inward and downward, but continues in a line with 

 the anterior portion of the jaw, and the coronoid process rises 

 abruptly from behind M 3 , with no depression for the dental 

 foramen. The incisor is small, M 3 is smaller than M 2 , and the 

 tooth row is long in proportion to the rest of the jaw. 



