In the continuation of our investigation of the phytochemical constituents of Malagasy liverworts, a new cuparane-type sesquiterpenoid together with five known compounds was isolated from Bazzania decresens. Bazzania madagassa furnished a new cyclomyltaylane-type sesquiterpenoid and a new acoradienol. The structures of the isolated compounds were determined based on a combination of physical and spectroscopic evidence. The chemosystematics of the genus Bazzania as well as the biogenesis of cyclomyltaylane sesquiterpenoids in liverworts is discussed.