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Nautilus
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.
Caroline Is.:
Recently Mr. C. N. Cate presented me two walkeri from Moen Is. in the Truk Is. (coll. Schilder No. 17135 and 17136); they
formerly belonged to a series of fifteen similar shells dredged by R. Willis in the harbour in January 1962. These two shells
are "pellucid" like the dead glossy cowries dredged in Honolulu harbour, and exhibit a similar white chalk in the aperture:
there, the conditions of preservation in the harbour of Moen Is. must be about equal to those in Honolulu. The specimens
undoubtedly belong to walkeri (surabajensis) and not to bregeriana: the discovery of this far-off population of walkeri in
the central Caroline Is. is not very surprising, as other typically Malayan cowry species also spread to western Micronesia,
e.g. Erronea ovum Gmelin and E. onyx Linnaeus to Palau and Guam respectively.
Northern Melanesia:
Mrs. K. Matcott of Mooloolaba, Queensland informed me by letter in March 1963, that she possesses a "surabajensis" from New
Britain; as I have never examined the shell personally, the reliability of this indication seems to need confirmation.
Fiji:
Mr. W. O. Cernohorsky has quoted walkeri bregeriana from New Caledonia and Fiji, in his recently published Catalogue of
Living Cypraeidae (Frankfurt-Main 1963). In fact, since 1962 at least eight bregeriana have been collected in Fiji, all off
the West Coast (Nadi and Momi) facing towards the chief habitat of bregeriana, New Caledonia; especially Mr. A. Jennings has
dredged, at the islands Wading, Akuilau, and Namotu (20 miles off Nadi) several dead and living specimens, one oliviform
shell included of which I could examine the radula (Mr. Cernohorsky presented me a shell from Momi, coll. Schilder No. 17154,
which is 17 mm. long). All specimens show the typical orange base, often darker brown in the center of the inner lip, and the
peculiar white specks on base and margins, but they are much smaller (16 to 21 mm., mean 18 mm.) than typical bregeriana from
New Caledonia (20 to 33 mm., mean 25 mm.). These shells look like a population displaced far from its original habitat in New
Caledonia, where bregeriana is less rare, to an area with less favorable environments, as it is in the two dwarf Erosaria
ocellata Linnaeus from Tjilanat Eureun, South West Java widely separated from their Indian relations (see 1938, Prodrome, p.
138).
South East New Guinea:
If bregeriana could spread from New Caledonia to Fiji, it probably also could spread to North West: therefore I now do not
doubt its occurrence in Joanett Is., Louisiade Archipelago, from which locality Smith (1888, Journ. de Conchyl. 36:313) has
described three bregeriana of 21 to 22 mm.
The indications of habitat: Persian Gulf, Red Sea, Victoria, New Zealand, and Tahiti evidently are erroneous.
The appended map clearly shows the advancement of our knowledge concerning the distribution of Erronea walkeri since World
War II. It should encourage malacologists to further research.
Having a special interest in mollusks of the West African coastline, I have inquired as to why shells from that area are
often so difficult to obtain. The above pictures graphically show the reason.
The natives of the area seem to have a real passion for the use of sea shells as personal decorations, many collectors'
treasures being used as ornaments.
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