Abstract
A preparation in the Ehrenberg Collection was designated as lectotype of Ceratoneis closterium Ehrenb., the type of the name of the genus Ceratoneis. The lectotype specimen was studied using the light microscopy and found to agree morphologically with recently studied material of taxa of the genus Cylindrotheca Rabenh. (1859) observed by Reimann & Lewin (1964). Ceratoneis Ehrenb., having priority over Cylindrotheca Rabenh., is reinstated and appropriate transfers are made.