The sporophyte structure of Cavicularia densa Steph. was investigated and described in detail with photomicrographs. Taxonomic and phylogenetic discussions, based on the sporophyte features, are made on the genus Cavicularia, as well as on the genus Blasia. Characters newly noted include the bulbous foot, a rudimentary collar at the base of capsule, semiannular or helical thickenings of the inner capsule wall, several layers of transfer cells on both sides of the placenta, and the presence of a single large plastid in the early stage of the sporocytes. The occurrence of monoplastidic sporocytes in both Cavicularia and Blasia strongly support their inclusion is the family Blasiaceae in the metzgerioid liverworts.