北日本海諸島ノ藻類分布ニ就イテ (豫報)

Here I treated Sadogasima, Awasima, and Tobisima as the islands of the northern Japan Sea, having 880sq. km., 9.3sq. km. and 2.3 sq. km. respectively. Although very small they are, except the island Sado, these islands occupy important situation on the distribution of the marine algae. They are extended from 37°48′15″ to 39°12′18″ of the north latitude. These islands are quite warm for their northerly situation, their average temperature being 13.2°C., 13.3°C., and 12.5°C. respectively in 1935, owing to the Tusima-current, running closely along them, although branches of the LIMAN-current and Tisima-current give some contrary effect.<br>Up to the present time the reports on the marine flora of these islands are very poor, and so far our knowledge concerning the marine flora is obtained to some extent from the works of Dr. K. OKAMURA, Dr. K. YENDO, and Mr. M. NAKAMURA. In general the study of the marine algae in the northern Japan Sea, both in these islands and along the coast of Honsyu, is still in an initial stage. I have studied these several years on the distribution of the marine algae of the northern Japan Sea. With this object I visited Sadogasima (Island Sado) in July 1933, Awasima in Aug. 1935 and July 1936, and Tobisima in July 1931, June 1936 and July 1936. The reports on the distribution of the marine algae in Awasima and Tobisima respectively have been published elsewhere by the author recently.<br>1. The species here enumerated are 157 in number, of which 18 belong to Chlorophyceae, 53 to Phaeophyceae and 86 to Rhodophyceae. Among them, 19 species are left for future study on determining the species names, and also *-marked species have not yet been collected by the author, but they are abstracted from several literatures.<br>2. From the point of view of algal distribution, in general, almost 75% of the species enumerated here are of the warmer sea, 6% of colder, 7% cosmopolitan, the remainder being unknown.<br>3. The species which are endemic in Japan proper are 81 in number., those common to Australia, Malay Archipelago and Polynesia are 30, those common to North America (Pacific coast) 18, and those common to all Europe 24, 8 being cosmopolitan almost all over the world.<br>4. Among them the following 10 species are peculiar to the Japan Sea: Ecklonia stolonifera, Cystophyllum caespitosum, Sargassum confusum, S. Turneri, Coccophora Lansdorfii, Grateloupia divaricata, Nemastoma Nakamurae, Chondrus affinis, Crouania divaricata, Laurencia nipponica.<br>5. The 20 species numbered 13, 18, 22, 35, 44, 46, 47, 60, 82, 86, 104, 106, 109, 110, 124, 125, 129, 139, 152, 156 in the accompanying table may be regarded as the typical southern elements, while the 8 species numbered 8, 37, 40, 43, 49, 120, 121, 142 can be regarded as the northern elements.<br>6. From the point of view of geographical distribution, so far 11 warmer species are recognized as having Sadogasima as their northern limits, while 8 species Awasima and 14 others Tobisima as their northern limits.<br>7. Some of the species which have hitherto been treated as produced only in the Pacific coast were discovered on the coast of Japan Sea, such as: Dictyota spinulosa, Heterochordaria abietina, Sargassum Horneri (TURN.) C. AG. f. furcatodentatum, Myelophycus caespitosus, Nemalion pulvinatum, Lithothamnion laeve FOSL. f. tenuis, Jania adhaerens, Polyopes Polyideoides, Hypnea musciformis, Polysiphonia Stimpsoni, Laurencia obtusa LAM. var. majuscula.