274 



BULLETIN 56^ UNITED STATES NATIONAL MUSEUM. 



of the subgenus Parasclurus. The brain case is bi'oad, high, and swol- 

 len, much as in Sclurus grlseus antJumyi and S. ahertl. The f rontals 

 are flattened, almost concav^e in front, but strongly bulging posteri- 

 orly. The postorbital processes are long and deflected. The interp- 

 terygoid fossa is long, as in the fox squirrel, measuring considerably 

 more in length than the combined lengths of the three upper true 

 molars. Incisive foramina long and narrow. Audital bulhi? large. 

 Greatest length of skull (t3''pe), 60 mm. ; greatest breadth, 34. De- 

 tailed cranial measurements are given below: 



Vranial inr(tHHreinciits< of N K[)ccimc)is of Sciurus arizonensis. 



a American Museum of Natural Historv. 



Ilahits and local dhtrihiition. — Each of the four squirrels inhab- 

 iting Arizona has its separate habitat, none being generally dis- 

 persed. The Mogollon chickaree is confined to the fir and spruce 



