peridium

The fructification is a delicate netted plasmodiocarp, the tubule about .5 mm., bright red; the peridium simple, cartilaginous, dehiscent from above, and flecked with just here and there a red calcareous scale.

From The North American Slime-Moulds A Descriptive List of All Species of Myxomycetes Hitherto Reported from the Continent of North America, with Notes on Some Extra-Limital Species by Thomas H. (Thomas Huston) MacBride

When the spores are ready for dissemination a small aperture appears in the top of the peridium, through which they push their way outwards like a little puff of smoke.

From Student's Hand-book of Mushrooms of America, Edible and Poisonous by Thomas Taylor

Sporangia gregarious, clustered but distinct, sessile small, about .75 mm., bright yellow, peridium double.

From The North American Slime-Moulds A Descriptive List of All Species of Myxomycetes Hitherto Reported from the Continent of North America, with Notes on Some Extra-Limital Species by Thomas H. (Thomas Huston) MacBride

Gasteromycetes, in which the hymenium is enclosed in a second case or wrapper, called a peridium, which ruptures when mature, thus releasing the spores.

From Student's Hand-book of Mushrooms of America, Edible and Poisonous by Thomas Taylor

"Whether the thread is hollow or solid, simple or branched, free or connected with the peridium or a columella,—these are entirely secondary conditions, depending on the extent and form of the vacuoles."

From The North American Slime-Moulds A Descriptive List of All Species of Myxomycetes Hitherto Reported from the Continent of North America, with Notes on Some Extra-Limital Species by Thomas H. (Thomas Huston) MacBride