Originally published in 1941, this book was written to provide an elementary textbook on phycology suitable for university students and schools including visits to marine biological stations as part of their curriculum. Relatively few types are selected from each algae group; some are described in considerable detail whilst others are mentioned to illustrate the course of development in either the vegetative or reproductive organs. Illustrative figures are included throughout. This book will be of value to anyone with an interest in phycology and the history of science.