Hendricksen 1950 Uma scoparia Sept. 13 & 15 [mi. W. 8 mi. S. Pinto Mt.,] 1750 ft., Riverside Co., Calif. Two mornings on the dune have given little real acquaintance with the animal; the following fragmentary notes are all that seem definite enough to record: - distribution: On areas of fine, wind-blown sand only - not on areas where fine sand is mixed with gravel or rocks, and not on areas where fine sand has been pocketed by rain or runoff water. - activity: Began at about 8:00 A.M., when temp. of sunlit sand was about 40° C. Early, animals did not seem so disposed to run down holes as later, but more often stopped in the open. Late in the morning, they invariably seemed to disappear down Dipodomys deserti holes. Efforts to wait for them to reappear from the holes were fruitless. Two 20 min. vigils discouraged me. One concerted effort to dig out two adults seen to vanish down the same hole also proved fruitless. - location: on main dune, especially E. end, and on gentle slope E. & S. of W. & S.W. of main dune. - young: Several small individuals were seen, all rather early in the day.