L. Karsten 1954 Bufo boreas (25) May 13 stream meadow, 4000ft., Yosemite Valley, Mariposa Co., Calif. 1-2" deep with dark brown sandy mud bottom had about 30 Bufo toads in it. No Hydra here. Water now appears clear of oil although grasses surrounding the small pool are oil-covered and dying or dead. Grasses out in deeper water have oil on them but are green and apparently surviving. Bufo toads collected far from spot described. Water temp 1" below surface 6" from pond edge; 12:58 P.M. (D.S.T.) 27° C. Air temp 1" above ground, bulb shaded, 27.5° C. Pond temp out in middle, depth 8", bulb 1" below surface 25.2° C. 1:04 P.M. (D.S.T.) There seems to be a definite Bufo preference for shallower water. They also tend to congregate on surfaces of light submerged objects or pieces of cardboard. These may be responses to O₂ tension or temp. (?) This noted before ponds were oiled, too. Small toads grazing on grass stems and bottom detritus. Algal development in Pond A is extremely weak. One Hydra adult on graze surface half immersed in water at 1:15 P.M. (D.S.T.) In full sun. This animal may have been under graze at edge of pond and moved out as I disturbed it. I saw 3 larger (1" long) Hydra toads eating one smaller dead Hydra. In this deep poor pool the dead toad may be important source of food, I did not recover in my sweeps large numbers of dead toads, and I saw none on the