588 



MERRIAM 



zygomatic breadth to basal length is 84 (essentially the same as in the 

 type of the species, from the Wind River Mountains, Wyoming) ; in 

 the two oldest females it is about 81.5. The mean interorbital breadth 

 in the males is 46.^ ; in the females 38.7. The sexual differences are 

 well shown in the following table : 



TABLE OF AVERAGE OR MEAN CRANIAL MEASUREMENTS. 



Mean of males 



Mean of females... 



190 

 160.4 



01 o 

 08 



n 



cd>S 

 o cQ 



*J3 

 CO ho 



6 "= 



i 155-5 67.5 

 155-6,130.1; 56-6 





99 

 83.1 



3 oj 



p a I 

 Sol 



a a ( 





05 



q ti 



II7.2 46.5 199 65.5 

 99.537.8:1685 56.1 



P-d 





►3 >, 



150 24 



126.7 21.6 



77/^ teeth. — The teeth which show sexual differences to best advan- 

 tage are the canines and carnassials. The diameter of the upper 

 canine (measured on the cingulum) varies in the males from 14 to 15 

 mm. ; in the females from 1 1^ to 12^ . The length of crown of the 

 upper carnassial varies in the males from 33 to 25 mm. (mean 24) ; 

 in the females from 30.2 to 22.5 (mean 21,6). 



INDIVIDUAL VARIATION. 



The skull. — Individual variation in this series is less than was ex- 

 pected. The differences in size of the two perfect male skulls (amount- 

 ing to 12 mm. in basal length and 15 mm. in zygomatic breadth) ap- 

 pear to be attributable to age, the smaller one being a young-adult with 

 practically unworn teeth ; the other a very old male with much worn 

 teeth. In the females, individual variation in size is more marked. 

 The largest and the smallest females are both young-adults with only 

 slightly worn teeth; one has a basal length of 157 mm.; the other 

 of 172 mm. — a difference of 15 mm. 



The parts of the skull presenting the largest amount of individual 

 variation are the nasal bones, the breadth of frontal across postorbital 

 processes, the breadth of postorbital constriction, and the audital bullae. 

 The nasal bones in the two perfect males measure respectively : 

 length 58 and 53 mm. ; breadth between tops of premaxillae 30 and 29 ; 

 breadth between maxIlUe posteriorly 20 and 16. In 4 of the 8 females 

 the nasals are surprisingly uniform, the length falling beteen 45 and 

 46 mm.; breadth between points of premaxillte 24 to 26; breadth 



