Max Egon Thiel's monographs on Scyphozoa (Cnidaria) and a left-behind typescript on the Rhizostomeae.

Max Egon Thiel worked as curator of the aquatic invertebrates collection at the Zoological Museum in Hamburg until 1963. Specialising in marine planktonic megafauna, he compiled a broad review of the research history on the Scyphozoa (Coronatae, Cubomedusae, Semaeostomeae) including the Staurozoa (as Stauromedusae), written in German. After publishing major parts in 1936 and 1938, World War II delayed further chapters until 1959 and 1962. A complete bibliography covering references up to 1970 was not printed until 1977. The final section on the taxon Rhizostomeae was completed as a typescript before his death, but was never published. In the present paper, the authors provide a synopsis of the published volumes in English. Following Thiel's original outline, the research history, as well as reviews of the current knowledge at the time about morphology, histology, ontogeny (life cycle), physiology, ecology, and phylogeny of the taxa are presented. The paper is complemented by two electronic supplements: A translated and revised version of the left-behind typescript of Max Egon Thiel about the taxon Rhizostomeae, and the revised digital list of references published in Thiel (1977).