The Sclerodermitaceae, or so-called hard puffballs, have been very inadequately studied by American mycologists. Indeed it has been too common a custom to group all the material together as Scleroderma vulgare Hornem, without regard to external markings, the thickness of the periderm, or the mode of rupture for spore dispersal. Probably one of the most comprehensive treatments of the American forms is that by Lloyd in connection with his studies on Australian species. His treatment has been followed with some variations by Hard and by McIlvane, each adding variations to the treatment of species. Several of the eastern forms have ben figured by Murrill in Mycologia. However, no systematic account of the American forms has come to the notice of the writer
