A Hitherto Undescribed form of Adult Axis in the Genus Batrachospermum

Abstract

THE genus Batrachospermum has always attracted interest as one of the few freshwater members of the Florideæ and on account of its distinctive appearance. Notwithstanding a general familiarity with the external form and early development of Batrachospermum, it has not been recognized previously that the old axes of some species may appear "solid" in transverse section, either all or almost all trace of the primary central filament of cells being lost. Such a condition has been found to exist in three species of this genus (Fig. 1), and there is no reason for doubting that subsequent investigation may show it to occur in other non-ephemeral species. The three species mentioned have not been identified with certainty as comparison with type specimens has been impossible in present circumstances, but two undoubtedly belong to the Helminthoidea section of the genus. Only male plants of the third species, the one here illustrated, have been seen and hence its affinity remains in doubt.