Voles of the Subgenus Chilotus. 



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Mmsurcments. — Type specimen (9 adult): total length, 131 ; tail verte- 

 brae, o3; hind foot, 17.5. A young adult rf from type locality: total 

 length, 130; tail vertebra?, 32; hind foot, 17. 



Microtus serpens sp. nov. 



Ti/pe from Agassiz, British Columbia. No. 76303, (J' ad., U. S. Nat. Mus., 

 Biological Survey collection. Collected December 2, 1895, bj' Clark P. 

 Streator. Original No. 5068. 



General characters.— SiraWar to M. oregoni, but tail much shorter ; color 

 darker; pelage mnch softer and longer (10 mm. or more on back in win- 

 ter specimens) ; ears buried in the long fur. 



Color. — Upper parts very dark l)rown, becoming almost duskj' on pos- 

 terior half of back, and everywhere profusely mixed with black-tipi)ed 

 hairs ; under parts dark plumbeous, the belly washed with ashy or butfy : 

 tail dusky above, pale below, and faintly edged and tipped with wdiitisli 

 when seen from above (due to the projection of the whitish hairs of tlie 

 under side). 



Cranial cJiaracter.^. — .Skull similar to that of ^[. oregoni, but slightly 

 larger; interorbital region less 'pinched in;' interparietal tapering off 

 more gradually on each side ; teetli larger ; crowns of molar series longer. 



Measurenieiits. — Type specimen: total length, 130; tail vertebra), 31 : 

 hind foot, 18. .\verage of seven specimens from type locality : total 

 length, 130; tail vertebrae, 32; hind foot, 17.5. 



