Secondary chamberlets in Cycloclypeus

Graphs, showing the relation of the primary chambers to the number of their secondary chamberlets, demonstrate that Tan's nepionic mutants are variable, even in the course of a short period. The evolutionary change of the nepionic mutants is consistent with the evolutionary change of Cycloclypeus as a whole. The number of secondary chamberlets of the first neanic chamber is considered a valuable characteristic for the identification of species. Reduction of the number of nepionic chambers in the course of time is thought to result from the occurrence of 'transitional nepionic variants'.