umbilicate

Sporangium globose, the base slightly flattened or umbilicate, stipitate; the wall a thin membrane, covered with small scales of lime, yellow or greenish-yellow, breaking up and falling away at maturity.

From The Myxomycetes of the Miami Valley, Ohio by A. P. (Andrew Price) Morgan

P. 1-1.5 cm. whitish, umbilicate striate; g. adnate to stem; s. 3-6 cm. black, glabrous, polished; sp.

From European Fungus Flora: Agaricaceae by George Massee

Sporangium depressed-globose, the base umbilicate, stipitate; the wall a thin, violaceous membrane, brownish at the base, with a thin coat of small, white scales and minute granules of lime.

From The Myxomycetes of the Miami Valley, Ohio by A. P. (Andrew Price) Morgan

P. compressum                             ++ Sporangia typically globose, umbilicate below, connate, etc., strongly calcareous 39.

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

Sporangium globose, the base sometimes flattened or slightly umbilicate, stipitate; the wall a thin, pellucid membrane, covered with small scales of lime, white, cream-colored, or sometimes pinkish, breaking up and falling away at maturity.

From The Myxomycetes of the Miami Valley, Ohio by A. P. (Andrew Price) Morgan