Dorsally, the conotheca is composed of an inner prismatic layer and a layer that corresponds to the lamellar layer. No nacreous layer is observable either in cross fractures or in longitudinal fractures.
Sideward from the paired ridges on the outer surface of the rostrum, the lamellar layer is 4-5 |im thick. Laminae were sometimes replaced by presumably phosphorus granules similar to those described by Doguzhaeva and Mutvei (2003). They are nearly 1 |im in diameter.
Mid-dorsally below the paired ridges the layer under discussion swells up to a spindle-like bulge of 40 |im in thickness (Fig. 14.6A). The spindle has a length of 500 |im. Here the lamellar layer is preserved as secondary calcite (Fig. 14.6B).
Was this article helpful?