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Shelltiles
From radula studies it would appear that bregeriana is a subspecies of walkeri after all, and not a separate species as I
always believed. However, it is open to doubt if radula comparisons are the only criterion in deciding a shell's specific
identity. Besides, bregeriana and walkeri are closely allied, and no large differences were to be expected. It is Dr.
Schilder's opinion, that there are no constant differences in radula between the species allied to arabica, and only few
species of Erosaria have peculiar characteristics. On the other hand, among 20 C. stolida from Shimoni, six showed distinct
central denticles in the middle of the median tooth, yet fourteen specimens showed no trace and the difference was not due to
sexual differences. Such a difference according to Dr. Schilder could be treated as generic almost and the difference in
radula of C. bicolor sometimes exceed usual subgeneric differences. It appears that the radula of a species is as variable as
the shell itself, and it seems to me, that the live animal's colour of foot, mantle, papillae and tentacles are more constant
than both radula and shell. Out of over 2000 Cypraea specimens I collected in Fiji for radula studies, only 6 specimens
showed a gross colour difference from the usual colouring of the species.
We can therefore regard bregeriana as a very good subspecies of walkeri, one that is in the transition stage of becoming a
species.
of Comparative Zoology at Harvard. Thus Richard Johnson in 1949 was able to select neo-holotypes for C. semiplota and C.
unifasciata and a lectotype for C. insecta.
1 Johnson, R.I., 1949. Jesse Wedgewood Mighels with a Bibliography and a Catalogue of his Species. "Occ. Pap. on Mollusks," 1
(14).
The "Ecological Niche" Of The Golden Cowry
Before you read this article, let's explain what it's all about. The "Ecological Niche" is a rhetorical expression understood
by most scientists and all malacologists. To the uninitiated, here is a homemade definition. It is not really a "niche" in
the generally understood meaning of the word. Instead, in Malacological lore, it is a description of a hypothetical location
where, if all the factors entering into the ideal conditions of living were present, that shell, and that shell only would be
found there. And that shell in this case is Cypraea aurantium Gmelin, 1791, which is referred to as the Golden Cowry.
The "Ecological Niche" of the Golden Cowry, or to put it in other words, the conditions under which it thrives, may be
described as follows: It is found only in the tropical Pacific Ocean, in the caves and crevices on volcanically formed land;
on the seaward side of reefs in water of maximum salinity at average depths of 25 to 35 feet; it is herbivorous living on
algae; it is nocturnal in its feeding habits; mature specimens average in length about three and a half inches, or around 90
millimeters. Width is around two and a half inches and the height is generally more than two inches; in color it ranges from
deep to lighter shades of orange. It is almost always found in pairs, and its natural enemies are sharks and violent storms.
The writer's theory is that the shell originated in the Solomon Islands.
Some amplification and discussion of the various items in the above paragraph may prove of interest.
Two Belgian scientists, whose hobby is conchology, have done some remarkable shell collecting along the Brazilian Coast of
South America. They are Dr. Bernard "Ben" Tursch, 29 years old graduate in bio-chemistry from the "Ecole Polytechnique"
University te'Libre de Bruxelles, and Dr. Jean Pierret, 32 years old and a graduate anthropologist, also from the University
of Bruselles.
Ben Tursch is working for Stanford University of California in Brazil where he is investigating the chemical structure of
some natural products. In his spare time, he collects shells and has over 300 species of Conus alone. Tursch hopes to publish
a catalogue on Brazilian marine shells with the help of local collectors.
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