This paper illustrates type material for both Tetracyclus japonicus (Petit) Temp. et Perag. (=Stylobiblium japonicum Petit) (Sendai, Japan, Fossil, possibly Miocene) and Tetracyclus eckhardii Ehrenberg (Ostheim, Germany, Fossil, age unknown). While it remains possible to confuse the two species, the latter (Tetracyclus eckhardii) has not been recorded since Ehrenberg’s description in 1848.