sentences:  In their 1962 monograph on North American "Calvatia", mycologists Sanford Myron Zeller and Alexander H. Smith set "C. craniiformis" as the type species of the stirps (a grouping of related species) "Craniiformis", containing species with a large sterile base and a persistent cottony gleba.Other species they included in this stirps were "C. umbrina", "C. diguetti", "C. lycoperdoides", "C. rubroflava", "C. ochrogleba", "C. excipuliformis" (since transferred by some authorities to "Handkea"), and "C. elata".