Meanwhile differences in consistency appear in various strata, and a dense outer protective layer (peridium), soft gelatinous layers, and so on are formed, the whole eventually attaining great complexity - e.g.
A more complicated case is illustrated by Sphaerobolus, where the entire mass of spores, enclosed in its own peridium, is suddenly shot up into the air like a bomb from a mortar by the elastic retroversion of a peculiar layer which, up to the last moment, surrounded the bomb, and then suddenly splits above, turns inside out, and drives the former as a projectile from a gun.
The teleutospore, with the sporidia which arise from it, is always present, and the division into genera is based chiefly on vulgaris, with a, aecidium fruits, p, peridium, and sp, spermogonia.
P. Petersii has a transversely divided basidium as in Auriculariaceae, but the basidia are surrounded with a peridium-like sheath.
The fruit-bodies are of very varic. as shapes, showing a differentiation into an outer peridium and an i:..ier spore-bearing mass, the gleba.
In the last-named genus the peridium is double and the outer layer becomes ruptured and spreads out in the form of star-shaped pieces; the inner layer, however, merely opens at the apex by a small pore.
Vulgaris, with a, aecidium fruits, p, peridium, and sp, spermogonia.