Just read a paper about abnormal hyperstrophy in larval Melania
tuberculosa, wherein 2 specimens in the brrodpouch of a female yielded
2 pseudosinistral specimens, both injury-freaks probably caused by
sudden contcation of the female into her shell, damaging the
youngsters within.

I remembered a specimen Vivienne Smith sent me, from Cape Coral, Fort
Myers, which proved to be full of juvenile shells, so dug the vial out
any yes indeed, there were 2 hyperstrophic specimens among them! One
appeared to be a sinistral shell of normal proportons (hyperstrophy
can do this, but the shells are DEXTRAL and only appear to be
sinistral) and the other is planorboid.

Such injury freaks occur especally in Lunella smaragdus, Sarmatorbo
sarmaticus and "Turbo" cidaris. Lanistes is an example of
normally-hyperstrophic species, as are Limacina, Peracle and most
Planorbidae (the latter being sinistral and therefore appear dextral).
Hyperstrophy means that coiling translates along the shell axis toward
the posterior.

Most other shells, when they appear dextral or sinistral, are really
what they appear to be (orthostrophic ie coiling translates along the
shell axis toward the anterior).

--
Regards
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
Mollusc, Toyota & VW van fan

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