Abstract
The history and taxonomy of T. tonsurans are presented. Morphological studies of 13 recent isolates as well as of 12 named "species" of the crateriform group from culture collections gave a varied picture; however, serial transfers of single spore strains gave evidence that similar morphological characteristics occurred at random among the isolates. Correlation with physiological studies, previously reported for these strains, suggested that cultures studied were variants of a single sp., T. tonsurans. The synonymy of this sp. is presented with 46 refs.