In frogs (Rana temporaria) the evoked potentials and the neuronal responses to stimulation of the optic nerve have been found in the lateral geniculate, posterocentral, posterolateral and posterior thalamic nuclei of the contralateral side. Responses to stimulation of the sciatic nerve have beenfound bilaterally in the posterior thalamic, posterocentral and posterolateral nuclei. In the primordium hippocampi bilateral responses have been registered after the stimulation of the optic and sciatic nerves and a number of diencephalic structures. Bilateral destruction of lateral geniculate, posterocentral, posterolateral and posterior thalamic nuclei abolished the visual responses in the primordium hippocampi. Somatic responses in the primordium hippocampi disappeared after bilateral lesions of the posterior thalamic nucleus and of the caudal parts of posterocentral and posterolateral nuclei. These areas are considered as relay nuclei of visual and somatic telencephalic pathways.In frogs (Rana ridibunda) unilateral lesions of the caudal part of the dorsal thalamus were made. In sections stained according to Fink and Heimer and with the modified Bielshowsky-Viktorov methods, the terminal degeneration was found in the primordium hippocampi of both hemispheres.