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Virgellar meshworks and sicular spinosity in Llandovery graptoloids

Published online by Cambridge University Press:  01 May 2009

R. B. Rickards  and
T. N. Koren'
R. B. Rickards
Affiliation:
Sedgwick MuseumCambridge CB2 3EQEngland
T. N. Koren'
Affiliation:
T. N. Koren' VSEGEILenigrad V-26U.S.S.R
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Summary

Orthograptus obuti sp.nov. and Orthograptus insectiformis Nicholson are shown to exhibit a complex proximal meshwork developed from a much-divided virgella which closely resembles retiolitid clathrial and lacinial networks. The virgellar meshworks tend to enclose the rhabdosome, at least for the first few thecal pairs, and may support a tenuous periderm. This kind of virgellar complexity is contrasted with a newly discovered form of sicular spinosity represented by the species Glyptograptus (Pseudoglyptograptus) tabukensis sp.nov. and G. (P.) rhayaderensis sp.nov

Type
Articles
Information
Geological Magazine , Volume 111 , Issue 3 , May 1974 , pp. 193 - 204
Copyright
Copyright © Cambridge University Press 1974

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