142 Osgood — A New White- Footed Mouse From Alaska. 



Skull. — Most similar to that of oreas, but nasals and rostrum averaging 

 slightly more slender; similar to that of keeni, but more lightly built 

 throughout; rostrum and nasals longer and more slender; posterior nasal 

 endings usually exceeding premaxillse; infraorbital region lighter; some- 

 what similar to that of macrorhinus , but decidedly smaller. 



Measurements. — Average of 20 adult topotypes: Total length, His. 4 

 (191-205); tail vertebrae, 98 (91-105) ; hind foot, 23 (22-23.5); ear from 

 notch (dry), 15.3.(14.5-16.8). Skulls of type aiid one topotype, respec- 

 tively: Greatest length, 26.9; 27; basilar length, 21; 21; zygomatic 

 width, 13.2; 14; interorbital constriction, 3.8; 3.9; interparietal, 9.6 x 

 3.2; 9.4 x 3; nasals, 10.5; 10.9; shelf of bony palate, 4; 4.2; pala- 

 tine slits, 5.9; 6; diastema, 7.5; 7.4; postpalatal length, 0.1; 8.8; max- 

 illary toothrow, 3.7; 3.0. 



