Gray and Thornton's strain (ATCC 17041) of Mycobacterium coeliacum, here designated as the type strain of this species (which was later transferred to the genus Nocardia as Nocardia coeliaca), is a strain of M. rhodochrous (tentative generic assignment). The strain producing the antibiotic nocardin and similar strains, however, have been mistakenly labeled N. coeliaca. This report presents some of the characteristics of 27 of these mislabeled strains and demonstrates their close relationship to the type strain of N. autotrophica (Takamiya and Tubaki) Hirsch. The nocardin-producing strain and others like it are, therefore, assigned to N. autotrophica.