RésuméThe amygdaloid nuclei of the rat and mouse were studied, and the confusion in classification and nomenclature was revised and corrected. thereby certain new division and terminology being introduced.The main mass of the amygdala (AP) is divided into three parts. Fkh of them shows two subd visions, which seem to be genetically different. This is especially distinct in the intermedial part (Afi). The medial part (Apm) is small in dimension in rodents studied.The so‐called ventromedial nuclear group, viz. the medial nucleus (D ofVölsch, the cortical nucleus ofJohnston, the nucleus B+D (basaler Spitzenkern) ofVölsch. the nuclei B and D “of the same author. the nucleus of the lateral olfactory tract (D‘ ofVölsch). were included all in the amygdala superficialis (Asf) in the present account, owing to its location and developmental aspect.Völsclt'snucleus B is not single mass of the same cytological character, as this is also the case with his nucleus D, the cell feature being pretty different from each other in the oral and caudal portions. In the house rat a fairly circumscribed mass of small cells, newly termed nucleus amygdalae parvocellularis corticalis. can be seen in the superficial amygdaloid area in the caudal half of it. In the mouse another type cells with fairly distinct arrangement were recognizable on the contrary in the anterior level of the amygdala direct caudal to the nucleus of the lateral olfactory tract, newly named ’nucleus arnygdalae magnocellularis corticalis' and likely homologous to the nucleus D” ofVölsch. In comparison with another rodents these two nuclei can be regarded as specifically characteristic in the rat and mouse.The term ‘amygdala intercalata’ (Ain) has been given to those groups of small cells, which envelop the main mass of the amygdala especially in its oral half. In the anteromedial aspect of the amygdala it forms a large nucleus. nucleus intercalatus ofGurdjian.The central nucleus ofJohnstonand those found in the dorsal aspect of the main mass of the amygdala are summarized in supraamygdala (SA). Ln its oral portion and apart from the so‐called central nucleus, which makes a prominent structure in rodents, a peculiar dense group of cells is found, to which the name nucleus supraamygdalae anterior is given. SA is evidently induced from the striatal matrix in an early embryonal period.Investigations on embryonal materials of the mouse show that both processes of pallial and non‐pallial developments are intimately concerned with each other especially in the caudal part of the main amygdaloid mass, the anterior part of the latter being apparently formed by the forward growth of the posterior part. Through all embryonal stages it seems that non pallial elements, emerging from the ependymal layer of the ventricle, play a dominant role. This view is not in agreement to th