rust has fallen in all.

Fig. 6 _a_. A single sporangia, enlarged to show columella, x 20.

_Physarum nicaraguense_ Macbr., p. 83.

Fig. 7. A group of sporangia, x 15.

Fig. 7 _a_. Capillitium, strongly calcareous, x 800.

Fig. 7 _b_. A single spore, x 1200.

See also Pl. XVII., Figs 11 and 11 _a_.

[Illustration: PLATE XV]

EXPLANATION OF PLATE XVI

_Physarella oblonga_ (Berk. & C.) Morgan, p. 109.

Fig. 1. Fully opened sporangium, x 10.

Fig. 1 _a_. Tubular sporangia closed, x 5.

Fig. 1 _b_. Transverse section of sporangium; shows trabecular
calcareous nodules of the capillitium, x 15.

_Craterium cylindricum_ Mass., p. 106.

Fig. 2. Group of sporangia, x 10.

_Physarum wingatense_ Macbr., p. 72.

Fig. 3. Group of sporangia, x 10.

_Physarum albescens_ Ellis, p. 86.

Fig. 4. Group of sporangia, x 10.

Fig. 4 _a_. Capillitium of the same species, x 200.

_Dianema harveyi_ Rex, p. 238.

Fig. 5. Group of sporangia, x 10.

Fig. 5 _a_. Clustered spores, D. corticatum, x 500.

Fig. 5 _b_. Capillitial threads and spores, D. harveyi, x 200.

Fig. 5 _c_. Twisted, spirally striate single threads, x 500; _D.
corticatum_, List.

_Physarella oblonga_ Berk. & C., p. 109.

Fig. 6. Terrestial, plasmodiocarpous phase, x 10.

_Physarum megalosporum_ Sturg., p. 63.

Fig. 7. Group of sporangia, x 8.

Fig. 7 _a_. Capillitium and spores, x 150.

_Didymium complanatum_ (Batsch) Rost., p. 116.

Fig. 8. Capillitial structure, x 200.

_Physarum wingatense_, p. 72.

Fig. 9. Sporangium, x 20, enlarged to show dehiscence.

_Didymium xanthopus_ (Ditm.) Fr., p. 123.

Fig. 10. Sporangium--diagram to show columella, x 20.

_Didymium eximium_ Pk., p. 124.

Fig. 11. Group of sporangia, x 10.

Fig. 11 _a_. Section of sporangium, x 30; diagram.

Fig. 11 _b_. Spore, x 750.

Comatricha elegans (Racib.) List., p. 182.

Fig. 12. A single sporangium, x 20.

Clastoderma debaryanum, p. 191.

Fig. 13. Sporangium, seen in section, x 20.

Stemonitis herbatica Pk., p. 171.

Fig. 14. Group of sporangia, x 2.

Fig. 14 a. The same enlarged to show general outline.

Fig. 14 b. The same; capillitial section, x 20.

Fig. 14 c. A single spore, x 1000.

[Illustration: PLATE XVI]

EXPLANATION OF PLATE XVII

_Cribraria argillacea_ (Pers.) Schrad., p. 218.

Fig. 1. Sporangium, highly magnified.

_Cribraria macrocarpa_ Schrad., p. 219.

Fig. 2. Sporangium, highly magnified