While working for several years on Palaeozoic Bryozoa with the aim of establishing the Palaeozoic stratigraphy of the Altai Mountains on the basis of the Bryozoan faunas, I have always been aware of a great contradiction. The works of American authors showed clearly that the stratigraphic importance of the Bryozoa is not inferior to that of any other group of fossils, whilst in the works of newer European authors the Palaeozoic Bryozoa were not only deprived of any significant rôle, but often even quite ignored. Owing to this, there arose a question whether the Palaeozoic Bryozoa have a universal distribution like, for instance, the Brachiopoda; or whether there is in North America a special Bryozoan fauna of stratigraphic importance locally, but absent from other parts of the globe. The study of the Siberian Palaeozoic Bryozoa showed a number of forms so far known only from North America, and this suggested that the apparent absence of “American” forms in the other parts of the globe is owing to the lack of intensive study given to the Palaeozoic Bryozoan faunas outside North America. Through the kindness of Dr. Nalivkin, who handed over to me several Bryozoa collected by him in the Middle Devonian of Germany, I was able to confirm this suggestion and I decided to examine, if possible, the existing collections of Palaeozoic Bryozoa of Europe. This appeared the more necessary because, although Palaeozoic Bryozoa were originally described by European authors, yet the species described by them were quite ignored by later American writers. Clearly then, if a comparison of the European with the American Palaeozoic Bryozoa were made, it would be likely that the trivial names of some American species would be replaced by the prior trivial names of European species. To make this comparison, I visited during the winter of 1928–1929 some of the most important museums of Europe, in which I could find either the type specimens of the European Bryozoa, or merely rich collections of topotypes. A revision of the material contained in the museums of Berlin, Munich, Bonn, Prague, Paris and London wholly confirmed my view, namely, that the “American” forms of Palaeozoic Bryozoa were universally distributed, but hitherto had been described and figured, often quite incorrectly, as distinct genera.