When the genera Myalina De Koninck and Naiadites Dawson were first established type species were not designated. As commonly happens the original concept of these genera is somewhat at variance with the characters of subsequently designated genolectotypes. In the present study the holotype of the type species of Myalina has been examined and found to be quite different from the current concept of De Koninck''s Myalina. Typical material of Naiadites reveals very close resemblance to Myalina. Nevertheless continued recognition of both genera seems to be practicable.