Plankton collections from 58 lakes of the Prince Albert Park and the southern half of Saskatchewan yielded 292 species and varieties of algae, among them Chaetoceros Elmorei, Nodularia spumigena, and a new variety of Lyngbya Birgei. The lakes, chemically alkaline, are classified as freshwater and saline, and the various classes of algae are briefly discussed with reference to these two types of lakes. A list of the species collected is given, showing localities and relative abundance of each type.