Tom and Paul,

Thanks for all the information. A fascinating topic, maybe because
albinos  are strange as well as beautiful and we are drawn to the
strange and mysterious.

Speaking of strange and mysterious, the name of one of the two books on
the famed melanistic cowries of New Caledonia (See Frank Walker's
melanistic cowry collection for sale) is Pierson and Pierson's 1975
Porcellaines Mysterieuses de Nouvelle Caledonie. Melanism seems to be
the converse of albinism.  I have seen quite a large number of these
cowries, oddities of color and shape.  While their distortions of shape
are not related to our evolved topic of albinism and pigment, the color
peculiarities are. The animals seem, through some environmental cause,
no doubt, to lay down excessive amounts of pigment in their shells.
Some become almost completely black.  However, this black color is not
always as simple as it would seem.

Cypraea cribraria, the Sieve Cowry, is normally noted for its white
shell overlaid with red. The overlay is solid red, except for discrete
and fairly regularly spaced round holes through which the unpigmented
white shell shows through. In New Caledonian waters, the shell pattern
on some individuals becomes distorted so that the red areas do not
remain discrete, but overlay the white areas in varying amounts. I have
seen a series of these freaks, from near normal to almost full "black."
More and more red pigment is laid down until the unpigmented white
spots, in extreme individuals, simply disappear. What is more, the red,
in such intensity, appears black and these red cowries are called
melanistic. Yet it is not melanin that is the pigment here. It is the
red pigment.  This happens in other cowry species lacking melanin in
their normal shells.

I have seen a Cypraea moneta, the little yellowish Money Cowry,
extremely affected by whatever the deforming and discoloring factor is,
to the point where the dorsum, from end to end, has so much yellow
pigment that it looks like a stripe of school bus paint!

Is all melanism due only to abnormal *black* pigmentation? Paul
suggested that the terms albino or albinistic can refer to any inability
to secrete normal pigment, even if the albino is "a blue frog." Is this
true of the term melanism too.

Lynn Scheu
Louisville KY
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