History of British animals - University of Guam Marine Laboratory

( 538)THECATA.I. Sheath slight/// calcareous ; cells single, or in rows.1. Sheath slightly calcareous, cells enlarged, in rows, united or single-—CELLARIADiE.a. Cells united.aa.b. Cells with the orifices opening on the upper surface.Cellularia.Tricellaria.Crisia.bb. Cells in pairs, attached by the back, the orifices withCells single.Eucratia.opposite aspects.Notamia.Anguinaria.II. Sheath membranaceous, cells enlarged externally and lateral. —SERTULARIADiE.I. Base of the cells broad, coalescing with the stem.a. Cells on opposite sides of the stem.Sertularia.Dynamena.Thuiaria.aa.Cells unilateral.Antennularia.Plumularia.Serialaria.II.Base of the cells narrow, or pedunculated.Campanularia.Valkeria.Cymodocia.III. Sheath membranaceous, the cells are the simple extremitiesof the branches.—TubulariadjE.Tubularia.Plumatella.