Fig. 2 _b_. A spore, x 1400. _Comatricha aequalis_ Peck, p. 180. Fig. 3. A single sporangium, x 10. Fig. 3 _a_. The columella and capillitium, x 60. Fig. 3 _b_. A single spore, x 1600. Figs. 3 _c_ and 3 _d_. Sporangia to which the peridium still adheres, although in 3 _c_ in shreds. _Stemonitis fusca_ Rost., p. 160. Fig. 4. A group of sporangia, x 3. Fig. 4 _a_. A part of the columella and capillitium, x 60. Fig. 4 _b_. A single spore, x 1400. _Stemonitis axifera_ (Bull.) Macbr., p. 168. Fig. 5. A group of sporangia, x 3. Fig. 5 _a_. A single spore, x 1400. Fig. 5 _b_. A part of the capillitium with columella, x 60. _Stemonitis splendens_, p. 164. Fig. 6. A group of sporangia, x 3. Figs. 6 _a_ and 6 _c_. Single spores, the latter x 1400. Fig. 6 _b_. A part of the columella and branches, x 60. Fig. 7. A shorter variety of the same species with coarser meshes in capillitium, x 3. Fig. 7 _a_. A part of the columella and net, x 60. [Illustration: PLATE VI] EXPLANATION OF PLATE VII _Diachaea splendens_ Peck, p. 187. Fig. 1. Sporangia and hypothallus, x 25. Fig. 1 _a_. Capillitium, x 50. Fig. 1 _b_. Spores, x 900. Fig. 1 _c_. Portion of the capillitium, x 150. _Didymium nigripes_ Fr., p. 123. Fig. 2. Sporangia, x 30. Fig. 2 _a_. A spore, x 1400. Fig. 2 _b_. Calcareous crystals from the peridial wall, x 750. _Didymium melanospermum_ (Pers.) Macbr., p. 121. Fig. 3. Sporangia, x 10. Fig. 3 _a_. A single spore, x about 1000. _Diderma testaceum_ (Schrad.) Pers., p. 137. Fig. 4. Sporangia; the first exhibiting the two peridial walls and the spore-mass, x 10. Fig. 4 _a_. Spore, x 750. Fig. 4 _b_. Capillitial threads, x 750. _Diderma globosum_ Pers., p. 134. Fig. 5. Sporangia; the first with the outer peridium broken away, x 10. Fig. 5 _a_. A single spore, x 750. _Mucilago spongiosa_ (Leyss.) Morg., p. 114. Fig. 6. An aethalium, borne on a grass-stem, natural size. Fig. 6 _a_. A spore, x 750. Fig. 6 _b_. Capillitium, with surface calcareous crystals, x 750. _Diderma crustaceum_ Peck, p. 135. Fig. 7. A mass of clustered sporangia, to show habit of aggregation, natural size. _Tubifera ferruginosa_ (Batsch) Macbr., p. 206. Fig. 8. A single spore, x 1400. [Illustration: PLATE VII] EXPLANATION OF PLATE VIII _Diderma floriforme_ (Bull.) Pers., p. 143. Fig. 1. Sporangia of various ages, x 5. Fig. 1 _a_. Spore of the same species, x 1000. Fig. 1 _b_. A capillitial thread, x 1000. _Physarum polycephalum_ Schw., p. 95. Fig. 2. The sporangia, x 10. Fig. 2 _a_. Spores, x 750. Fig. 2 _b_. Capillitium, x 750. _Leocarpus fragilis_ (Dicks.) Rost., p. 112. Fig. 3. Sporangia, x 6. Fig. 3 _a_. A group of sporangia, natural size, to show habit. Fig. 3 _b_. A single spore, x 1800. _Physarella oblonga_ (Berk. & C.) Morg., p. 109. Fig. 4. A single sporangium, x 8. Figs. 4 _a_ and 4 _b_. Capillitium and spore respectively, x 900. _Craterium leucocephalum_ (Pers.) Ditmar, p. 105.