1911 1 Taylor: Mammah of the 1909 Nevada Expedition. 283 



Cranial measurements show somewhat similar differences. 

 The series from Nevada is smaller in all respects (see table of 

 measurements) except the interorbital constriction and width of 

 rostrum posteriorly. An examination of the skulls shows that 

 the rostrum in or eg onus is shorter and broader than in major, 

 the skulls are smaller, the zygomatic arches are not so wide- 

 spreading, and the interorbital constriction appears broader. 

 The last-mentioned point shows up remarkably in the smaller 

 skulls. The interpterygoid fossa is narrower and more rounded 

 anteriorly in oregonus. The thin arm of the malar is stronger in 

 Oregon us than in major. There is a slightly greater inflation of 

 the parietal and temporal regions in the skulls of major. 



The young of orego^ius are very similar to the adults, though 



Cranial Measurements op Zapus princeps oregonus, From Pine Forest 

 Mountains, Humboldt County, Nevada. 



For method of taking measurements, see Introduction. 

 All dimensions are in millimeters. 



"" Measured from posterior margin alveolus of incisor to most anterior 

 point post-palatal notch. 



t Measured from inferior lip foramen magnum to most anterior point 

 post-palatal notch. 



X Measured perpendicularly. 



§ Measured just anterior of i)oint of junction of zygomatic arches with 

 the skull. 



§§ Measured at anterior end. 



