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概要

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Glycymeris (Veletuceta) albolineata are characterised by having the white radial lines and the rows of punctations, and are discriminated from G.(V.) vestita by the presence of the punctations scattered over the shell surface. The punctations are in two to four rows between two neighbouring white radial lines and are also in a line along the growth line. They do not distribute within 1 cm. from the ventral margin towards the dorsal side and gradually become indistinct near there. The distribution field of the small canal structures also coincides with that of the punctations. Comparing the inner surface of the shell to the limit of the distribution field of the punctations and the small canals, their distribution is limited inside the pallial line, that is their distribution coincides with the limit of the distribution of the inner layer. Small canals are scattered both inside and outside a punctation but several large canals are always found in a punctation. These canals are larger in width near the shell surface but in deeper part of the shell they have the same width as the smaller canals scattered outside the punctations. Thus the punctations might be assumed as the structure which was formed by several peculiar epitherial processes of the mantle after the shell formation had been finished.
地学団体研究会の論文
1970-09-25