1955 年 68 巻 807 号 p. 241-247
Yamadaia, a new genus proposed in the present paper, is a very curious articulated coralline. It was discovered by the writer on the coast of Izu Province. The erect part of the species is reduced to one joint only and the crust is so vigorously developed that, at first sight, it is mistaken for a non-articulated coralline. The node is unizonal and formed only between the crust and the joint. Thus, the erect part is represented only by a single joint bearing a conceptacle. The conceptacle-bearing joints are scattered on the surface of the crust. As in crustaceous Corallinaceae, the crust is made up of three layers: the epidermis, the perithallium and the hypothallium. The marginal meristem of the crust is composed of one layer of the long oblong cells and is not covered with an epidermal layer. Only transverse canals are found between cells belonging to different filaments and no morphological connexions are found among cells of the node. The conceptacle has an openning on its top and belongs to the terminal type. The roof of the conceptacle is built up of a special growth of the tissue around the bottom of the young one. The female conceptacle is long obovate in external form, and its cavity is ovate in section. The procarp is composed of one basal cell, one carpogonial branch and one or two sterile cells. The gonimoblast filaments are produced only from the margin of the thin fusion cell. The male conceptacle is long spindle-shaped in outline, and the beak is so long that the conceptacular canal is very long. The spermatangial mother cells are produced not only from the bottom but also from the lateral wall of the cavity. The tetrasporangial conceptacle is long obovate as in the female one, and the cavity is circular in section. The sporangia issue only from the bottom, and are surrounded by paraphyses few in number, in their young stage. The above mentioned respects show that the present genus has a close relation to Jania on the one hand, and to Corallina on the other hand. The anatomical characters rather suggest an intimate relation to Corallina.