284 Vniversiiij of California Vublicaiions in Zoology. L^'^'- 



Cranial ^Ieasurements* of Zapus major From the Warner Mountains, Modoc County, 



California. 



For metlidd of taking measurements, see Introduction. 

 All dimensions are in millimeters. 



Locality 



Parker Creek, 5500 ft. 



Parker Creek, 5500 ft. 



Parker Creek, 5500 ft. 



Parker Creek, 5500 ft. 



Parker Creek, 5500 ft. 



Warren Peak, 8700 ft. 



Parker Creek, 7300 ft. 



Parker Creek, 5500 ft. 

 Average of the males 

 Average of the females 

 Average of all the adults 



* For special modes of taking measurements see table immediately preceding. 



they present softer fur and a relatively greater number of black 

 hairs on the sides. It is very difficult to formulate differences 

 between adults and young from a study of skins. It is necessary 

 in every doubtful ease to examine the teeth and skull to deter- 

 mine age. In young adults or in juvenals it is impossible to draw 

 a line definitely separating the color of the back from that of the 

 sides, but this is not a character of youth exclusively, some of 

 the unquestioned adults of our series displaying it. One young 

 female (no. 7998) is slightly graj'er than the adults. 



A glance at the table of external measurements shows the 

 dimensions of males and females to be nearly the same. The list 

 of ratios draws attention to the fact that the various M-estern 

 species of Zapus are very similar in respect to proportionate 

 external measurements, i.e., ratios of length of tail V('i'tel)rae 

 and bind foot to total leiigtli. Orajoniix from Nevada diil'ers 

 almost as much in this respect from any other species in the 

 group as these species differ from each other, being apparently 

 nearest mould mis. In I'iict. our specimens of or<(/oinis froin 



