I have read in several places that species with varices produce the
next entire intervarical shell and varix in one go. One even claimed
that the apparent growthlines are not growthlines!

If you look at a variciferous muricid or epitoniid shell it is
obvious that this is not the case; there are quite ordinary
growthlines, for which the only mechanism whereby they can be
produced is by normal incremental growth. Muricids with unfinished
(hollow, thin) varices are not uncommon.

Rearranging my overseas ellobiids this evening, I came across 2
specimens of Pythia scarabaeus which I collected under large items of
litter by the side of the main highway in Fiji in 1995.

One specimen has an extremely thin last intervarical wall and last
varix bearing no apertural denticles. The other has only HALF of the
intervarix formed, also extremely fragile. The indication here is
normal incremental growth of the outer layers of the shell,
subsequently thickened by inductura ("enamel" inner layer).
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
<[log in to unmask]>
Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
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I want your sinistral gastropods!
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Opinions in this e-mail are my own, not those of my institution
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