258 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. i. 



SUBGENUS CHILOTUS. 



12. Microtus morosus. 



Microtus morosus. Elliot, Pub. Field Col. Mus., Feb. i, 1899, 

 p. 227. 



This form of Microtus is generally distributed throughout the 

 mountains, and it was obtained at all our camps when we were 

 collecting specimens, save one, but the greatest number were 

 procured at Happy Lake. As I mentioned in the remarks accom- 

 panying the original description (1. c.) it has some resemblance 

 to M. serpensTAerr., but the differences exhibited both in the color 

 of pelage and diversity of skull make it readily recognizable. It 

 belongs to the nanus group of Microtus. Specimens procured 

 along the Elwah River present no differences from those obtained 

 at timber line of the high mountains. 



Nineteen specimens: Johnson's Ranch, Elwah River, 6; 

 Happy Lake, 12; Boulder Lake, i. 



The drawings exhibit the under surface of skull, natural size, 

 and the upper tooth row enlarged over six times. 



SUBGENUS LAGURUS. 



13. Microtus pumilus. 



Microtus pumilus, Elliot Pub. Field Colum. Mus., Feb. i, 1899, 

 p. 226. 



It was at the camp, in the vicinity of Happy Lake, that 

 this species was met with, and we found it nowhere else, 

 though undoubtedly it ranges over the mountains at, or above, 

 timber line. Only three specimens, none fully adult, were ob- 

 tained among the large number of the Muridae procured through- 

 out our journey, and it is fair to suppose it is rather rare, 

 at all events in the localities we visited. It is very small, 

 almost the very least of the species of microtus yet discovered. 

 When the first individual was caught, I was impressed with 

 the idea that it represented a new species, and every effort 

 was made to procure a series, but two more examples were 

 all we succeeded in securing. The fur is very soft, and rather 



