These Web pages make available to the public a large portion of Richard H. Zander's 1993 Genera of the Pottiaceae: Mosses of Harsh Environments. Bull. Buffalo Sci. Nat. Sci. 32. Not presently included are the cladograms, excluded and untreated taxa, updated list of genera, species and infraspecific taxa, bibliography, glossary, and index. We do include the introduction, discussions of characters, techniques, and evolution, keys to genera, and treatments of genera. Also available are the 113 plates of illustrations by Patricia M. Eckel. This Web site makes widely available a modern, significant exposition at the genus level of a large, diverse and broadly distributed family of mosses adapted in general to arid and otherwise difficult habitats. We are grateful to the Buffalo Museum of Science for permission to create an on line version of this work, funded by the U.S. National Science Foundation Grant BSR 8314843.