<p>This monograph is the result of years of field and indoor work. It is based on faunal materials collected by the author during his geological research in Altai. This material is manufactured by A. I. This is complemented by special collections from the best sections by Nikiforova. In addition to Altai, Lower Carboniferous bryozoans are also found in the Kuznetsk coalfield, near the city of Tomsk and in the Eastern Outer Baikal region. Materials from these areas were collected by different geologists, the most complete collection in the Kuznetsk coalfield was conducted by V. I. Yavorsky and A. P. Rotay completed it, while in the East and Outer Baikal region it was completed by G. N. Frederiks finished. Since in the two areas above, the material was not collected by Paleozoic bryozoan experts as in the Altai, the collection in the Kuznetsk coalfield is far less complete and abundant than in the Altai region, although the fauna of the Kuznetsk coalfield-where the Carboniferous sediments are weaker than fold deformations in the Altai region and are completely unaffected by contact metamorphism of intrusive rocks-is in better condition than the Fauna of the Altai region. In the Eastern Outer Baikal area, Lower Carboniferous outcrops containing bryozoans are distributed in an extremely limited area, so the amount of collection from this area is naturally small. In addition, due to strong structural changes and contact metamorphism of rocks in the area, materials from Transbaikal are poorly preserved. In the Lower Carboniferous in the Altai, a rather rare occurrence has been observed in large numbers across the entire section-from the bottom to the top of the Lower Carboniferous. In the Kuznetsk coalfield, bryozoans are mainly concentrated in the middle of the Lower Carboniferous, but are relatively rare in the upper and lower levels; while in the East and Outer Baikal area, bryozoans of the Lower Carboniferous only appear in a relatively small section of the strata in the middle. Mining and smelting extensive and diverse materials from the Lower Carboniferous bryozoans in the Altai region laid the foundation for the author to establish a new method for studying Paleozoic bryozoans in the Soviet Union. In 1919, while conducting geological research in the mining and metallurgical Altai, the author noticed abundant bryozoans in two different parts in the best Carboniferous section of the Altai near the village of Tarhansk, and during field observations It has been obvious that the bryozoans in these parts are different. Prior to this, based on preliminary identification of brachiopods, the section near the village of Tarhansk was difficult to divide, and it was not even clear which part of the section was older. This situation prompted people to pay attention to bryozoans and try to use them as a basis for stratigraphic division of the section. European paleontologists once believed that Paleozoic bryozoans were not suitable for detailed stratigraphic division, but the work completed by Ulrich at the end of the last century to prove the value of Paleozoic bryozoan stratigraphy has received almost no attention in Russia or Europe. Therefore, the author's attempt to establish a Carboniferous stratigraphy of the Altai Region based on bryozoans was initially met with extreme skepticism. In the early stages of creating a new method for bryozoan research, A. I. Nikiforova provided the author with great help. Her active participation, patience and perseverance in this work greatly facilitated the selection of the correct (microscopic) path for studying Paleozoic bryozoans, thus revealing their significance for stratigraphy, which revolutionized geologists 'view of the fauna. As mentioned earlier, before the author began studying Altai bryozoans, Paleozoic bryozoans were almost completely ignored. In the best case, when an area is abnormally rich in bryozoans, the list of fauna will mention "and bryozoans" in the description of the area's profile. By the way, in Western Europe, this situation has not been eliminated yet, and references to "abundant bryozoans","bryozo-containing strata", etc. are often encountered in the latest writings, but genus names are rarely even given in the description. The author and A. I. Nikiforova jointly reviewed and initially identified a large number of materials collected from various parts of the Soviet Union. At the same time, it was found that the Lower Carboniferous bryozoans in Altai had many things in common with bryozoans contemporaries in the Kuznetsk coalfield and the East and Outer Baikal region, but at the same time, they were significantly different from the Lower Carboniferous bryozoans in central and eastern Kazakhstan and Central Asia, let alone areas further western in the Soviet Union. This is particularly evident in the bryozoans of the lower Douneian and Vyxian stages, which are rich in bryozoan characteristics throughout the Asian part of the Alliance. The differences are so obvious that it is impossible to confuse bryozoans from Kazakhstan or Central Asia with bryozoans from the Altai, Kuznetsk coalfields or Transbaikal. Interestingly, at the same time, in eastern Kazakhstan and the Altai Region, the distance between the nearest outcrops containing Lower Carboniferous bryozoans does not exceed 500 kilometers, while the distance between Altai and East and Outer Baikal in the shortest direction reaches 2500 kilometers. Interestingly, whether in Siberia, as well as in Kazakhstan and Central Asia, bryozoans are most abundant in the lower part of the Dunaean and Visianian stages, which seems to indicate their commonality, but the composition of the fauna in these areas is different. Of course, there are common characteristics between them, for example, typical of the central Lower Carboniferous: Fenestella serratula Ulr., F. multispiuosa Ulr., F. rudis Ulr.，However, these forms seem to be widespread in the central Lower Carboniferous, which does not prevent the division of Siberian bryozoans into an independent zoogeographic area. In this regard, other forms are more indicative. For example, for the Lower Duneian stage in Kazakhstan, the genus Piliopolella is very typical, while for the middle of the Lower Carboniferous in Kazakhstan and Central Asia, the genus Septopora; representatives of the latter genus can be found in almost any collection of small bryozoans brought from these places. In Siberia, the situation is completely different. The genus Piliporella has not been found anywhere there. As for the genus Septopora, only a few small fragments of the genus have been found among the thousands of bryozoan specimens in the Altai. Only one specimen has been found so far in the Kuznetsk coalfield, and none have been found at all in the eastern and outer Baikal. The Lower Carboniferous bryozoan species in Siberia, central Kazakhstan, and Central Asia, which is similar in terms of its bryozoan fauna, are also in the vast majority of cases different. For example, a comparison of bryozoans from the Tarhan Formation in the Altai (i.e., the bottom of the Lower Carboniferous) with bryozoans from the bottom of the Lower Carboniferous in central Kazakhstan-the Kasin Layer-shows that these fauna do not share a common morphology, and even the assemblages of their genera are significantly different. Interestingly, in Kazakhstan, in the lower half of the Duneian stage, no Reteporina genus so typical of the Altatatarhan Formation has been found at all. At the same time, in Kazakhstan and Central Asia, the genus Reteporina (the same species in both cases) is present in the upper Dunaean, while in other parts of the Altai and Siberian region the genus is not found in Upper Dunaean sediments. This work was completed in the spring of 1941, and since then relatively few works on Carboniferous bryozoans have appeared in the world literature, so no major revisions or supplements are needed. All the materials on which this monograph is based, with some exceptions specifically noted, are preserved in the Φ.Н. Monographs Department of Chernyshov Central Geological Museum (Collection No. 6398). The following abbreviations are used in the text: г о-Central Geological Museum in Leningrad РА -Mining and Metallurgical Altai FILDRA-Institute of Palaeontology of the Soviet Academy of Sciences in Moscow. The photographic illustrations of this monograph were produced in the Photography Laboratory of the All-Soviet Geological Research Institute. The maps were analyzed under a microscope with the help of ○.Ф. Razutkina's drawing device is completed. (This content is AI translation and the translation accuracy is not guaranteed. Please refer to the original text for details) </p>