The deposits of the Main Devonian field on the territory of the Russian platform represent an exceptionally favorable object for detailed research in a variety of directions. The beauty and richness of the fauna , with almost no change in precipitation , variety of facies and associated complexes of forms, constant migrations of fauna and their repeated change - cause perfectly exceptional suitability of deposits for staging paleontological and paleoecological studies , supported by accurate lentologicheskih data. 50 years ago, the deposits of the Main Devonian Field and their fauna were studied by P. N. Wen current. The latter properly assessed the specifics of the Devonian fauna of the Russian platform and, describing it, dwelled on a number of general issues, such as: the problem of the species, the question of the image and living conditions of the representatives of the Devonian fauna, the question of its appearance and disappearance, etc. p. With a sharp change of rocks in the section of the Devon on the southern shore of Lake Ilmenai with the accompanying rapid change of the faunal complex collided about 50 years earlier (in 1840 .). ), G. He was one of the first researchers of the geology of the present Leningrad Region .. He was also interested in the cause of this shift and the absence of some forms that are generally characteristic of Devonian other areas.