Comprehensive DescriptionRead full entry
Colony encrusting, unilamiar to bilaminar; or erect, frondose or arborescent, jointed or unjointed. Gymnocyst absent; frontal surface of autozooid membranous (apparent in fresh or dried material as a glistening sheet which appears continuous over the whole colony), membrane underlain by an extensive cryptocyst. The depressor (parietal) muscles of the frontal membrane pass through paired lacunae referred to as opesiules, occasionally forming distinct tubes by a down ward deflexion of the cryptocyst towards the basal wall of the autozooid. In Rosseliana and similar genera the semicircular opesia comprises about one-hird of the total length of the autozooid frontal surface and the opesiules are apparent as shallow notches in its proximal border. In a majority of genera the cryptocyst extends beneath most of the frontal membrane, the opesiules are completely enclosed and the opesia is reduced to a small, semicircular area distally, corresponding exactly with the operculum. Avicularia, ovicells and spines present or absent.
(Hayward and Ryland, 1998)