 He concluded that the "articulated apparatus" was a genuine molluscan radula, most similar to those of modern aplacophorans or gastropods.He then commented on the contrast between this apparatus and the two or rarely three widely spaced and more heteregeneous tooth-rows found in fossils of "Odontogriphus" and "Wiwaxia", and concluded that "Odontogriphus" and "Wiwaxia" were unlikely to be molluscs.However, a 2012 study re-examined the mouthparts of these two genera, and identified problems with previous interpretations.