260 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. i. 



probable that these are made in the winter, and consist of the 

 earth thrown upon one side, while the animal is making a pass- 

 age for itself beneath the snow, for the earth lies not only 

 upon the surface of the ground, but also upon limbs and 

 branches of trees scattered in the line of its route. At inter- 

 vals along these mounds are entrances to its underground gal- 

 leries, which descend directly into the earth, sometimes for 

 a considerable depth. This animal is exceedingly wary and 

 cunning, and for a long time we were unable to catch it. It 

 would not enter the traps, and when these were placed in an 

 excavation in the gallery, it would spring them every time, 

 or dig around them, and we despaired of ever succeeding in 

 capturing a specimen. At length Mr. Akeley constructed a figure 

 four trap, which would drive two spikes from above into the gal- 

 lery, and when the gopher attempted to cover with earth the 

 trigger that obstructed its path, the trap was sprung, and the 

 animal was caught. In this way about a dozen were captured, 

 but only two or three were ever taken from the same colony, 

 and it seemed as if the survivors, if there were any, deserted 

 the place, for no fresh workings would be perceived. It is 

 a small species, the total length varying from 198 mm. to 211 mm. 



Eight specimens: Happy Lake, 4; Boulder Lake, 4. 



The figures exhibit lower surface of skull (natural size), and 

 the upper tooth row, enlarged six and a half times. 



FAMILY 



15. Zapus imperator. 



Zapusimperator: Elliot, Pub. Field Colum. Mus., Feb. i, 1899, 

 p. 228. 



This large kangaroo mouse was quite plentiful in certain locali- 

 ties, especially in clearings on the banks of the Elwah River, 

 where grass seed had been sown by the owners of few ranches, 

 some of which, however, had been deserted for the more power- 

 ful attractions of the Klondike. They were very difficult to 



