Sea buds - Sea buds

Japanese: ウミツボミ(海蕾) - ウミツボミ

Blastoidea is an extinct class of stalked echinoderms that flourished from the Ordovician to the Permian period. It was so named because its shape resembles a plant bud. Its almost perfect radial symmetry is typical of echinoderms and distinguishes it from sea apples. It has a beautifully arranged 13 limestone plates and a tread with many finger plates. It is characterized by a water canal in the cavity under the tread, and is classified according to the developmental stage of the folded water vascular folds. The Pentremites (illustration) from the Carboniferous period of America is famous. [Morishita Akira]

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

オルドビス紀～二畳紀に栄えた有柄棘皮動物の絶滅綱Blastoidea。形が植物のつぼみに似るのでこの名がある。ほぼ完全な放射相称をなす点は棘皮動物の標式的な形態を示し，ウミリンゴ類と異なる。13個の石灰板がみごとに配列し，多数の指板をもつ歩帯がある。歩帯下の空洞にある水管が特徴であり，褶状の水管褶の発展段階によって分類されている。アメリカの石炭紀のPentremites（イラスト）は有名。【森下晶】

出典　株式会社平凡社世界大百科事典第２版について　情報

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