ABSTRACT Eggs of some archaic fishes, such as Polypterus, sturgeon or the holosteans, resemble amphibian eggs. Not only has the similarity been found in the amount of yolk (mesolecithal types of eggs), which indicates the manner of egg cleavage (holoblastic) in these vertebrates, but also in the morphological composition of yolk. Fat droplets, yolk platelets and an unidentified fluid in which they are suspended, in fishes sometimes called ichthulin, are three main components of yolk in these eggs.