Report on the Monaxonida collected H.M.S. Challenger during the years 1873-1876 / by Stuart O. Ridley and Arthur Dendy -- Report on the Myzostomida (Supplement) collected by H.M.S. Challenger during the years 1873-1876 / by L. von Graff -- Report on Cephalodiscus dodecalophus, a new type of the Polyzoa, procured on the voyage of H.M.S. Challenger during the years 1873-1876 / by William C. McIntosh