Includes bibliographical references (pages 235-270) and index.

Introduction -- Part I: Green algae. Chlorophyta ; Ulvophyceae ; Cladophorophyceae ; Bryopsidophyceae ; Dasycladophyceae -- Part II: Brown algae. Stramenopiles ; Phaeophyceae -- Appendix 1: List of new Taxa and combinations -- Appendix 2: Endemic Taxa of the Gulf of California that occur in the Northern Gulf -- Appendix 3: Algal specimens illustrated: species locality information and herbarium. The present treatment constitutes a taxonomic study of the green and brown benthic marine algae currently known in the northern Gulf of California. In all, 133 species were found: 4 classes, 7 orders, 13 families, 20 genera, and 63 species of Chlorophyta and 9 orders, 15 families, 26 genera, and 70 species of Phaeophyceae. The systematic account is a guide to the identification of marine algae from the northern Gulf of California, with the accepted name, keys, and descriptions of the orders, families, genera, and species. The date, place, and author(s) of valid publication of each taxon are cited. The current name for each species is given along with its basionym, type locality, synonyms, relevant taxonomic studies, habitat, and distribution in the Gulf of California and in the Pacific Ocean. Illustrations are provided for most species. A remarks section includes additional information on taxonomy, nomenclature, ecology, and/or other problems or facts of interest. In addition to reviewing the taxonomic phycological literature pertinent to the Gulf of California and Pacific México, new records and distribution extensions are given. Four new sections of Sargassum subgen. Sargassum are proposed: S. sect. herporhizum E.Y. Dawson ex J.N. Norris, S. sect. johnstonii E.Y. Dawson ex J.N. Norris, S. sect. lapazeanum E.Y. Dawson ex J.N. Norris, and S. sect. sinicola E.Y. Dawson ex J.N. Norris; five new combinations are made: Desmarestia munda subsp. mexicana (E.Y. Dawson) J.N. Norris, Epicladia condensata (Setchell et N.L. Gardner) J.N. Norris, Epicladia mexicana (Setchell et N.L. Gardner) J.N. Norris, Hincksia bryantii (Setchell et N.L. Gardner) J.N. Norris, and Sargassum sinicola subsp. camouii J.N. Norris et Yensen. One new species, Sporochnus neushulii J.N. Norris, is described.