Rana pipiens sphenoarhyncha Sept. 25. Nature Area, Chas. h. Tilden Regional Park, Contra Costa Co., Calif - At the bottom of the spillway draining Jewel Lake we found many frogs in a very large, pool. The pool was about 25 feet x 15 feet, roughly oval, and about 2 feet deep at the deepest. The spillway dropped sharply about 10 feet to the water and the bank to the east side was also quite steep. An elm tree had tipped over the pool, but was still growing. Its roots formed way across on the steep bank. The north bank was a more or less open, hard muddy beach sloping very shallowly into the pool, and the west bank was similar, but steeper and covered with bay rum (lavrel). Lavrel & elm were the predominant plants around, but there was also strawberry, horsetail ferns, and a little poison oak around. There was little vegetation in the water, but it had a slimy look, probably due to algae. Another dead tree was in the pool. It had fallen over and the roots were exposed. In addition there were many logs in sticks in the water, although the surface was mostly open. The water was quite cool (cold). The bottom was silty, with a considerable amount of leaf litter on it. Many beetles, hemipterians were in the water, and we got a larva aurisuptora. Conspicuous vertebrates were stickle backs and Rana aurora. We saw 3 pipiens and 1 or 2 aurora. There were more around down the creek, but no pipiens. Elry caught another specimen in Jewel Lake where it must coexist with R. aurora and catesbaia.