(B.) Davis 1935. Castle Creek, 8 mi. S Creana, Owyhee County, Idaho. May 27. rocky outcroppings and in another place were very abundant in an area of low grass entirely devoid of Artemisia. Their high pitched squeaks, much shriller than that of C. oreganus apparently is quite distinctive for this species. The animals were very shy for the most part and sought cover at the slightest sign of danger and it was with some difficulty that Iwining and I were able to collect a small series of 8 specimens. Most of these were what I should judge to be yearlings; that is, not old ones nor young of the year. An old female and a young of the year were taken for comparison. I believe they do not reach full maturity until at least the second year, though doubtless they breed the second year, that is when a year or less of age. This one large colony, perhaps covering a couple of square miles or more in extent, some of which appeared to be deserted dry farm land, was the only one we saw on the trip over here. They seem to be isolated in colonies and are not