Acknowledgments from S.R. Stidolph: Thanks are due to the U.S. Geological Survey for accepting the Stuart R. Stidolph diatom atlas for presentation on their web site. In particular I would like to thank Kathryn Smith for her enthusiasm and for the excellent results in presenting my images. Special thanks are also due to my old friend and collaborator Frithjof Sterrenburg for perusing the Atlas, offering helpful suggestions, correcting my omissions and generally improving on the text by his additional notes.

Acknowledgments from all authors: We are indebted to several staff at the U.S. Geological Survey for assistance in web presentation of the Atlas, including Theresa Burress for editorial and bibliographical research, Jolene Shirley for assistance in web development, and Janice Subino for graphic design assistance. Meghan Maraia, an intern from Eckerd College, provided assistance on species authority research and text edits. Also, the presentation was improved by careful reviews provided by Lisa Osterman and John Watson.

We are indebted to the thoughtful comments from expert diatomists, which greatly improved the information regarding species identities: Andrzej Witkowski, Jakub Witkowski, and Przemek Dabek from the University of Szczecin.