The results of interpretation of biostratigraphic separation of santonian-campanian deposits of the Saratov right-bank Volga region, on the example of earlier conducted detailed and complex investigation of separation near the village Mezino-Lapshinovka have been presented. The ideas of realiability of variants of the detailed (on the level of subtages) subdivision of santonian substage in reference to the territory of the Volga right-bank have been given.