The 42 intertidal transects established by E. Y. Dawson on the southern California mainland from 1956-1959 were resurveyed for their algal flora during 1973-1974. Although there were no losses of conspicuous species, the relative abundances of various forms had changed over the time period. The shift in the flora has been toward the turf and crustose species and away from the massive species. The Orange County flora showed the greatest change and the Los Angeles flora the least. In the Santa Barbara. Ventura, and San Diego areas the flora was modified to an intermediate extent.