Thacker 1958 Species account. Dipodomys merriami pg. 1 July 15 Mason Valley, 5.3 mi. W Vallecito Stage Station, San Diego Co., Calif. Took 4 of these in snap traps last night. They are much greyer than those I took two years ago near Agua Caliente. There is a very marked vegetational difference between these two places also. (see journal July) July 16. Had two more of these here this A.M. One of them is very markedly different in color from the other five, much paler. Three were frozen or dried to be put up later as we are moving on today. July 16 Vallecito Stage Station, (500± ft., San Diego Co., Calif.) I had two of these clips this a.m. (573-574) in a trapline set on the valley floor across the road from the stage station. The desert floor here is quite rocky and cut by numerous dry washes. The vegetation is sparse, a little ground cover. It is composed mainly of sotol chohua, barrel cactus, etc. These specimens frozen and prepared later. 5 mi. W Vallecito Stage Station ~ 1.4 mi. E., 3 mi. S Vallecito stage station, (350± ft., San Diego Co., Calif.) Took one clip in trapline that ran from the road across the desert to the large dry wash along the southwestern side of the valley. The soil here was finer, less rocky than that mentioned above. July 17 Tucson Mines, 700± ft., Pima Co., Calif.