Principal events in the early embryonic development of the nervous system, from neurulation to primary differentiation, are
considered in different amphibian species. Attention is paid to numerous interspecific differences in the structure of neuroepithelium
and the patterns of neurulation and embryonic brain segmentation. The data presented indicate that similarity in brain developmental
patterns is apparently explained by universality of morphogenetic mechanisms rather than by the common origin of particular
species. A hypothesis is proposed that similarity in the shape of the developing amphibian brain is determined by mechanisms
of coding positional information necessary for histogenetic differentiation.