The thermal and sub-thermal representatives of Cyanophycean algae from Beppu are numerous and include of all three orders. In the previous study I had found 73 species and varieties, and more four species have been found in the subsequent investigation. Thus I have found 27 genera and 77 species and varieties in all, and six of them are believed new t science. The most abundant genera are mastigocladus and Phormidium. At some sites the plants of these genera form extravagant strata of up to several centimeters thick. The species of Oscillatoria are exceedingly numerous in number and widely distributed in this region, but their significance in thermal flora is less than the former two genera. The species of Synechococcus, Chroococcus and Lyngbya are not uncommon ; while it is notable that those of Gloeocapsa, Calothrix, and Schizothrix are observed only a few. The hot springs of Beppu are divergent in chemical nature. Most of them, however, are simple or carburreted springs, and in such waters the thermal flora flourish most. Synechococeus, Mastigocladus, Oscillatoria and Phormidium are found most frequently in simple springs, while the species of Lyngbya, very few. In carburreted springs Chroococcus, Synechococcus, Mastigocladus, Oscillatoria, Phormidium and Lyngbya are found abundantly. In acidic springs Chroococcns, Oscillatoria grow abundantly, but Phormidium, very poorly. In hot water of particular nature only a few members of algae are found. The thermal Cyanophyceae of Beppu generally occur in waters neutral or slightly acidic. In this study the total range which the algae can thrive is pH 5,0-9,2. They occur most abundantly at about pH 6,0-7,0. The majority of the species are restricted to a range of 2,0 units or less, very few grow through a range of 3,0 units. The members of thermal blue-green algae occur abundantly at temperature 30-50 _. Above 60_ the abundance abruptly decreases. Several species such as Oscillatoria formosa, O. princeps, etc., show a wide temperature range. In this study the upper temperature limit is noted for O. formosa at 75_. Typical thermal forms which are found abundautly are as follows : Mastigocladus laminosus, Oscillatoria amphibia, O. animalis, O. formosa, O. geminata, O. Okeni, O. princeps, O. tenuis, Phormidium laminosum, Ph. tenue, Ph. valderianum. It is interesting that the species known from the tropics are found from the thermal springs of this region. They are Stichosiphon regularis, Nostochopsis Wichmannii, Calothrix brevissima, and Oscillatoria Lemmermannii.

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本屬の分類に於ては,蘚齒の構造が最も重要にして,標本惡しければ種類の決定殆んど不可能なる程度に有性世代に於ける特長の少き一群である.故に古人の發表せる種類にして,正しき精しき蘚齒の研究なきもの,或は子嚢なき標本にて書かれたるものには,その解決を他日に譲らねばならぬものもある.それ等を除外して著者が檢出し得たる七種につき檢索表を作れば次の如し.1. 口輪は1-2層,口輪細胞は同形,圓状多角形.2. 外齒は突出せる多乳頭の横條あり.内齒は外齒に引懸るか,或は完全に附着す.3. 内齒の齒片は外齒に引懸る程度にて齒脚に分裂せず.4. 子嚢は球状.5. 胞子は約35μ.翼細胞は小數にして,6-7列,7-8層.子嚢柄は15mm.に達す.…P. subcircinata CARD. 5. 胞子は30μ以下.翼細胞は最多數にして,10列,35層に達す.子嚢柄は一般に短し.…P. Brotheri BESCH. 4. 子嚢は卵圓筒状.胞子は約21μ.翼細胞は多數にして,7-8列,22層に達す.…P. Fauriei TOY. 3. 内齒の齒片は外齒に完全に附着する齒脚に分裂す. 4. 子嚢は圓筒形,直立.外齒の横條次種より弱し.…P. Cardoti TOY. 4. 子嚢は楕圓筒形,水平.外齒の横條強く多乳頭,長く突出して廣き舷をなす.…P. cristata CARD. 2. 外齒は乳頭殆んど無く,横條殆んど突出せず.内齒は外齒に附着せず.…P. sublaevidens TOY. 1. 口輪は三層,最上層細胞は強大にして倒卵形.外齒は外,内側共に多乳頭.横條無きに似たり.内齒の齒片は完全に外齒に附着する齒脚に分裂す.…P. laeto-viridis OKAM. マキハキヌゴケ (P. subcircinata CARD.).次種とよく似た植物にして,CARDOTは子嚢柄の長きこと,翼細胞の少數なることにより,次種と區別せり.子嚢柄は時には短くなることありて(form. breviseta),よき特長ならざるも,翼細胞の少數なることと,新しく特長として附加する點であるが,胞子の大なること,とは次種より明に區別するを得.本邦中部以北に多し.

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