 "Letognathus" was originally assigned to "Rhizodus" in the mid 1800s and later to "Strepsodus".This includes the species "Rhizodus" (now "Letognathus") "hardingi" of Dawson, named after a Dr. Harding of Windsor, Nova Scotia.Similarly, Dawson's "Acrolepis" is now attributed to "Elonichthys" and his "Palaeoniscus" is attributed to "Canobis".