A preliminary survey of caves located in the limestone belt of the Appalachian Valley of Virginia, has revealed the presence of numerous soil and water inhabiting species of aquatic Phycomycetes. A review of the literature indicates a paucity of information dealing with these organisms. The caves sampled and the methods used in this investigation are briefly described. From nineteen caves 162 soil and water samples were collected from which 33 isolates have been obtained. In addition a number of monocentric chytrids were observed, but have not been further identified. Each species isolated has been studied and described under unifungal cultural conditions. The occurrence and distribution of each species is cited and any variations in morphology or development are discussed. Questions dealing with the taxonomy and nomenclature are considered in each case. The cavernicolous environment may be regarded as a new station for each species reported herein. Three species of Pythium, P. afertile, P. irregulare, and P. nagaii, are reported for the first time as saprophytic inhabitants of the soil. / Master of Science