of sporangia, x 5.

Fig. 13 _a_. Sporangium tip, capillitium, x 200.

Fig. 13 _b_. Spore, x 800.

_Physarum compressum_ Alb. & Schw., p. 80.

Fig. 14. A group of sporangia to show compressed form, x 10.

See also Plate XIX., Fig. 12.

[Illustration: PLATE XVIII]

EXPLANATION OF PLATE XIX

_Dictydium cancellatum_ Batsch, p. 230.

Fig. 1. The finest phase, as the form appears in the Mississippi valley,
x 15.

Fig. 1 _a_. Sporangium of the same seen from below, x 35.

Fig. 1 _b_. Sporangium--same--seen from above, x 35.

Fig. 1 _c_. Cribraria-like net from the top, x 200.

Fig. 2. Vertical section of what is believed the typical European form,
x 20.

Fig. 3. An ellipsoidal piriform phase--var. _prolatum_, x 15.

_Physarum compressum_ Alb. & Schw. form _P. affine_ Rost., p. 80.

Fig. 4. A group of sporangia, x 12.

Fig. 4 _a_. A single spore, x 600.

Fig. 4 _b_. Capillitium, same species, x 300.

_Alwisia bombarda_ Berk. & Br., p. 209.

Fig. 5. Open sporangia, x 6.

Fig. 5 _a_. Sporangium of same enlarged to show capillitium, x 20.

_Cribraria dictydiodes_ Cke. & Balf., p. 222.

Fig. 6. A group of sporangia, x 6.

Fig. 6 _a_. Single sporangium of same--lateral view, x 25.

Fig. 6 _b_. Same; base view, x 30.

_Cribraria aurantiaca_ Schrad., p. 221.

Fig. 7. Single sporangium, x 30.

_Cribraria rufa_ (Roth) Rost., p. 220.

Fig. 8. Sporangium, x 30.

_Cribraria piriformis_ Schrad., p. 224.

Fig. 9. Sporangium, x 30.

_Cribraria splendens_ (Schrad.) Pers., p. 221.

Fig. 10. Sporangium, x 30.

_Echinostelium minutum_ DeBy., p. 198.

Fig. 11. Several sporangia, x 15.

Fig. 11 _a_. Vertical section, after Rost., x 500.

_Physarum compressum_ Schw., p. 80.

Fig. 12. Sporangium, x 20, to show dehiscence.

_Didymium anomalum_ Sturg., p. 127.

Fig. 13. Plasmodiocarps, about natural size.

Fig. 13 _a_. Diagrammatic vertical section, etc., to show the
calciferous pillars distinguishing the species, x 200.

Fig. 14. Calcic crystal--enlarged.

_Physarum sinuosum_ (Bull.) Weinm., p. 52.

Fig. 15. Plasmodiocarps passing to sporangia, x 5.

Cf. Plate VIII., 6 and 6 _a_.

_Physarum bitectum_ List., p. 53.

Fig. 16. Plasmodiocarps as in 15, showing transitional phases, x 10.

[Illustration: PLATE XIX]

EXPLANATION OF PLATE XX

_Badhamia iowensis_ n. s., p. 36.

Fig. 1. Sporangia several presentations, x 15.

Fig. 1 _a_. Capillitium, x 200.