Abstract

Linoproductus angustus King attached itself by its cardinal spines to a cylindrical object such as a crinoid column, bryozoan or productoid spine, and there remained suspended throughout its life. Attachment spines grew in pairs, one on each side, beginning first as indentations in the mantle at the posterolateral corners, then as tubes filled by mantle which extended toward the object of attachment. Spines are absent from other parts of the shell. The spat attached parallel to the object of attachment, but anterior growth produced near perpendicularity in mature adults. Apparently some shells lived with the pedicle valve uppermost, others with the pedicle valve down. The tip of the beak of the pedicle valve was the point of original attachment of the shell. It was thin and concave in juveniles, but thickened in adults to form a strong cicatrix that bore against the object of attachment. L. philocrinus Stehli is a junior subjective synonym of L. angustus.

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