Osgood Thirty New Mice of the Genus Peromyscus. 77 



Skull, About equal in size to that of P. laylori ; braincase narrower and 

 more elongate ; decidedly smaller than in P. musculus : nasals very short ; 

 audital bullse very small ; molar teeth small. 



Measurements. Type : Total length, 113; tail vertebrae, 47; hind foot, 

 14 ; ear from notch (dry), 9.7. Average of 6 topotypes : 104; 44; 13.4. 

 Skull of type: Greatest length, 18.4 ; basilar length of Hensel, 14.6; 

 zygomatic width, 9.6 ; interorbital constriction, 3.2; nasals, 6.3 ; inter- 

 parietal, 5.5 x 1.3 ; palatine slits, 3.7 ; bony palate, 3 ; upper molar series, 3. 



Remarks. This diminutive species occurs with P. musculus at Colima, 

 the type locality, and at other localities in western Mexico. It is repre 

 sented chiefly from the States of Colima and Jalisco, but its range has not 

 been thoroughly worked out and it seems quite possible that it may be 

 found over a considerable area. Apparently it is closely related to 

 P. paulus,* the description of which indicates an animal of about the same 

 size but of different color. 



* Allen, Bull. Am. Mus. Nat. Hist., XIX, pp. 598-599, November 12, 

 1903. 



