Vidal and Ford (1985) described a rich, well-preserved acritarch biota from the late Proterozoic Chuar Group in northern Arizona. The biota includes Chuaria circularis (Walcott) Vidal and Ford, whose diagnosis was emended. A SEM micrograph of a specimen supposedly deriving from the Kwagunt Formation of the Chuar Group was included (Vidal and Ford, 1985, p. 357). However, the figured specimen derives from the Late Proterozoic Eleonore Bay Group in east Greenland (Vidal, 1979, Pl. 4, a, b) and was erroneously included as a consequence of an inadvertent replacement of films during the preparation of paper prints for publication. The author of this note alone bears responsibility for this regrettable mistake.