Minute Thallophyta from the Akiyoshi Limestone, Japan

The present paper reports on a rich variety of microfossils obtained from the Akiyoshi limestone by chemical procedures. Microflora includes several kinds of algae and fungi-like bodies and spores. The yield of the fossils is very rich and their preservation is very good. In this paper, three new genera and four new species are described; they are Shimakuraea polysporangia, Confervoida akiyoshiana, Confervoida minensis and Sporophora multifulcata. The author could not determine whether they are algae or fungi, but they are supposed to belong to Thallohoypta. Because, their position in the taxonomical classification cannot be determined from only their external appearance. The criteria of classification of living algae and fungi cannot be applied to these Paleozoic fossils. However, these fossils have some resemblance to certain species of present Rhodophyta, Chlorophyta, Phaeophyta, Phycomycetes and Ascomycetes. The fossil-bearing limestone group ranges in age from Lower Permian to Upper Permian. Finding of these fossils will contribute to the paleoecology and sedimentology of the Chichibu geosyncline. The present paper deals only with thalloid fossils. Fossil spores will be described in the next paper