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THE MODE OF SECRETION OF THECAL AND EXTRATHECAL PERIDERM IN SOME ORDOVICIAN AND
SILURIAN GRAPTOLOIDS
Denis E.B. BATES and Nancy H. KIRK
In: Bjerreskov, M. & Stouge, S. (Eds.) Third International Graptolite Conference Abstracts, 1985, 1.
The construction of thecal and extrathecal peridermal structures in a number of Ordovician retiolitid graptoloids and
Silurian ancora bearing graptoloids is described in terms of secretion within a mantle of extrathecal tissue. The possible
function of some of these structures is also discussed.
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