R. Zweifel Oct. 5, 1932 89 Rana boylii boylii Muck Ck., 6.3 mi. SE Clayton, Contra Costa Co., Calif. Since my last visit here, number of cattle and horses have invaded the area, with the result that most of the grass and cattails along the stream bank have been trampled. The change in the character of the stream border has affected R. aurora more than R. boylii. 10 adult boylii were taken and young were very numerous. Only four aurora were collected and a few others seen. At one spot there was a pool 4' deep with a little aquatic and riparian vegetation around it. Two large aurora were taken from the pool, and at least two others were present. At the shallow end of the pool there was a sunny, sandy bar on which several adult boylii and numerous young were found. The habitat segregation holds, even though the frogs were only about 10-12' apart.