1. Fifteen whitefish Coregonus lavaretur from the Bothnia near Holmsund (Sweden) were studied. The fishes were very susooptiblet to infection and could be kept alive in aquaria for only 48 h. 2. Experiments with different preparation and anaesthesia methods indicated that the fixative penetrated the pharynx equally well whether the gill covers were removed or not. Blood vessels than of tized be traced more easily those decapitated without anaesthesia 3. For the first time, epibranchial organs in Euro- cies are described. A vestigial pean fish spe dorsal part of the organ was found close to the to the oesoph- fifth gill slit each side; it is connected organ agus by a pharynx groove. Each epibranchial flat consists of a diverticulum containing short and gill rakers, some of which may support the pharynx groove. Small papillae are situated in the opening of the organs. Epibranchial organs are ted by the support enlarged fourth epibranchial bone and the small fifth epibranchial cartilage associated with it; they are morphologically similar to those of the Canadian grayling Thymallus arcticus. in A. The function of the epibranchial organs Coregonus lavaretus is discussed and it is suggested that they receive and accumulate plankton which is then carried to the oesophagus via the pharynx groove. In this way the whitefish would be able to feed on plankton in addition to selecting larger food particles.