Examination of thin sections of trunk wall in an old specimen of Ikeda taneioides from Misaki, Sagami Bay revised previous false information about the wall musculature, actually consisting of outer circular, middle longitudinal, and inner-most oblique layers, like all other echiurans. This finding, together with the reexamination of relevant museum specimens, led to some taxonomic changes. These include that the definition of the genus Ikeda was amended to be a senior synonym of Prashadus; the family Ikedidae was regarded as a junior synonym of the family Echiuridae; and the order Heteromyota, erected virtually for I. taenioides, was abolished. Non-discovery of males and some other features in the amended genus Ikeda were noted with reference to its possible relationship with the family Bonelliidae.
