Since little or nothing has been published on mammals of this region it was deemed advisable to print a list even though very incomplete and based on preliminary and limited collecting in order to have some definite forward step in this much neglected line. Some of the mammals listed below have not been collected by us but are known to occur. Thanks are due Mr. H. S. Swaith for his kind aid in identification of some of the skins collected. Bears of course have long since disappeared but still have left their reputation among old mountaineers. The story goes that a bear, perhaps the last one, was killed at Bear Flats on the trail to "Old Baldy," hence the name. _Odocoileus hemionus californicus._ (Caton.) California Mule Deer. Fairly common through Upper Sonoran and Transition zones. They have been taken as low as the mouth of San Dimas canyon. The recently established game preserve assures an increase in the future. Already they seem to have sensed the protection for on May 19, 1916, we were surprised to find just 75 feet before us a large doe on the auto road not far above the first power house. _Ovis canadensis nelsoni?_ C. M. Merriam. Merriam Desert Bighorn. Mountain sheep have lived for years in the higher peaks above Claremont but being very shy and in inaccessible and little frequented parts have escaped attention very successfully. Rumor has it that Mountain Goats are found with the sheep but I believe this to be unfounded, having been originated probably by the sight of the smaller horned females and young. The area occupied by the sheep is a very definite one and comprises the peaks Ontario, Cucamonga, Telegraph, St. Antonio ("Old Baldy"), and Iron Mountain with their high rocky intervening ridges. Of the points mentioned the first three peaks are the favored ones. I found only a few tracks on Iron Mountain and a rumor of a pair of horns found there some five or eight years ago. "Old Baldy" being too often visited is not a frequented spot for the sheep, serving only as a connecting link to Iron Mountain. However signs around Ontario, Cucamonga and Telegraph peaks are abundant and anyone with a little patience and diligent endeavor can readily see the sheep themselves. They travel often in bands, as many as fifty and in summer keep to the highest places. Where they go in winter is as yet a mystery to me, probably lower into canyon heads for I have never found them on the top during this season. This of course is natural for these peaks practically become great ice mountains dangerous for anything to travel over. Besides grass the food consists of twigs and leaves of _Castonapsis sempewirens_, several species of _Ceanothus_, _Rhammus croceus californicus_, _Rhus trilobata_ and a parsnip _Pastinaca sativa_. _Citellus beecheyi._ Richardson. California Ground Squirrel. Abundant in all parts from brush land to 8,000 feet altitude in suitable localities.