ACKNOWLEDGEMENTS I am grateful to Charles Reimer and Ronald Mahoney of the Academy of Natural Sciences of Philadelphia for their prompt responses to my inquiries and for sharing their knowledge of diatom exsiccatae and their time during my visits to the Academy, to the Farlow staff for creating a most accommodating environment in which to work, to Donald Pfister for the opportunity to pursue this work and the patience to let me work at my own pace, to Monika Schuler for many jobs well-done, and to my wife, Susan, who would have much preferred the sound of piano keys, for being "staunch in learning's cause."