1. All three species are easily grown on artificial media. Mature fruit bodies were obtained only in cultures of Cyathus fascicularis. 2. The mycelia of all are very similar except for color. Clamp connections are abundantly present, and conspicuous mycelial strands are formed. The cells of Cyathus fascicularis are binucleate or composed of segments with paired nuclei. 3. The basidiocarps of Cyathus fascicularis and C. striatus arise from mycelial strands in all cases observed; while those of Crucibulum vulgare may arise from mycelial strands, dense mats of hyphae, or from the interior of old peridia. 4. The primordium of the basidiocarp seems to have its origin slightly below the tip of the strand, and consists of closely interwoven filaments smaller than those of the strand. 5. The first marked internal differentiation in all three consists of the gelatinization of a zone of hyphae in a region that will become a part of the inner wall of the peridium. A zone of closely interwoven filaments just to the i...