Belemnites are common throughout the boreal province of the Upper Cretaceous Series of Eurasia occurring at practically all horizons of the so-called Senonian stage (in the broader sense) nearly everywhere in this province; often they are the only group of fossils to be met frequently enough to be used for stratigraphical purposes. Despite this there have so far been relatively few efforts to use the Upper Cretaceous belemnites as zone-fossils, with the exception of some Actinocamax and Gonioteuthis species. The probable reasons for this regrettable neglect have already been mentioned in a previous paper (e.g. Jeletzky, 1946, pp. 87–90). Our researches, the results of which have till now only partly been published (e.g. Jeletzky, 1940, 1941, 1946) have shown that the Upper Cretaceous belemnites occur relatively frequently, and in the same stratigraphical order throughout the whole Eurasian boreal province and are in fact excellent guide fossils.