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Pecten vexillum orange
I have a Cypraea arabica niger Roberts (the racial name is in accordance with the Schilder's classification) which was
collected on the rusty hulk of a ship at New Georgia, Solomon Islands, a Cypraea mauritiana calxequina Melvill and Standen
collected on a sunken Japanese ship in Rabaul Harbor, New Britain by Harry Reiek, and a Cypraea maculifera Schilder collected
by John Souder near a rusty sunken ship at Berlin Island in the Marshall Islands. All of these are melanistic because of the
rust in the nacre which evidently was absorbed by the mantle and deposited in the nacre. The color of the maculifera was the
least affected and that of the mauritiana the most affected as the dorsum is a deep reddish brown. This did not effect the
base of any except the arabica, and on it there was some traces of the rusty color that extended a little on the base on each
side. This lack of effect on the base could possibly be another flaw in Cernohorsky's theory.
Conchologists have been puzzled for many years as to why cowries in certain areas are subject to melanism and rostration.
Some of the old time conchologists thought some were new species, and unfortunately some were described. For example, Cypraea
arabica niger was described as a new race.
Melanism and rostration rarely occur in Japan; rostration is rare in Okinawa and Torres Strait, and melanism never occurs in
Okinawa and Torres Strait to my knowledge. It is puzzling that the most complete melanism and rostration combined occur in
New Caledonia and Queensland both of which are near the Tropic of Capricorn. It is by far the most frequent in that latitude
too. It is a mystery why some species that live in the two areas most affected are never rostrate or melanistic.
I will diverge from the subject to some extent in the next paragraph, but it does concern the unusual in cowries.
Unknown factors in the environment seem to influence the size, color, and shape of cowries causing ecological variations and
aberrations. I have seen a Cypraea miliaris diversa Kenyon (=metavona Iredale) which was collected by Alex Schelechoff in
Moreton Bay, Queensland, which is so suffused with a uniform layer of white enamel that only by close examination can one
discern the dorsal spots. Alex deserves credit for noticing this detail as very few collectors would have noticed this. At a
glance it appears to be Cypraea eburnea Barnes.
The illustration [above] shows two Cypraea scurra Gmelin collected off Barbers Point. The specimen at the left has a complete
covering of an olive green color. As far as can he determined, the nacreous covering of the shell is identical to that of the
normal scurra on the right. Other collectors must have also collected similar shells. Is this melanism or a diseased
condition?
The first article in this series dealt with the collection of a live Golden Cowry, practically on order, by Francisco E.
Lahora of the Southern Philippines. This shell was requested by Dr. Alison Kay, General Science Dept., University of
Philippines, who wished to examine the soft parts microscopically. In the course of corresponding with Mr. Lahora, many other
interesting facts developed. We emphasize the word facts because in his letters Mr. Lahora insisted that he would give only
details which he could substantiate.
Unless the Philippines are included in Micronesia, and we believe they are not, the discovery of the Golden Cowry in the
Philippines is probably a range extension for this species. When Mr. Lahora sent the measurements of his first eight shells
to be registered in the Golden Cowry Register maintained at the Children's Museum, he mentioned, under the date February 5,
1962, that they were collected "in a period of more than a year between 1959 - 1960." Subsequently we learned that three
additional specimens had been taken, the one sent to Dr. Kay being No. 11. Except for No. 11 these shells were always found
in pairs. He spent an extra hour trying without success to find the mate of that one. All were taken at night, in
comparatively shallow water (not over 5 fathoms), "under ledges in the coral reef a little bit off the tidal zone." The
locality was the coastal town of Manay on the Pacific shore of Davao Province, southernmost Philippine Island of Mindanao.
This island lies about seven degrees north of the equator.
Mr. Lahora has kept a very close check on the Golden Cowries found in his province, and here is his report on that subject:
The photograph reproduced above represents the holotype of Gisortia gisortiana pterophora SCHILDER (1927) from the Middle
Eocene of northern France (Boisgeloup near Gisors); it is 26 cm. long (about 10.4 inches). The curious lateral appendices and
the dilatation of the posterior beak are absent in Gisortia gisortiana PASSY, the length of which varies from 22 to 29 cm.,
so that the unusual characters of pterophora may be interpreted as a sign of beginning degeneration. The photograph was been
made by Mr. V. J. Stanek (Prague) in 1928; an exact drawing of three views of this specimen has been published by the writer
in 1930 (Proc. Malac. Soc. London vol. 19, pl. 11, fig. 14-16). But Gisortia gisortiana is not the largest cowry: the last
representative of the group destined to become extinct is Gisortia hoernesi LEFEVRE from the Upper Eocene (Priabonian) of
northern Italy of which inner casts only are preserved: but the shell must have been at least 35 cm. long (14 inches).
There is still another group of fossil cowries which tend to gigantism, and are even more interesting to malacologists
studying living species only: for it is geologically younger than the Gisortiinae, and it is closely allied to a living group
of species . Zoila (Gigantocypraea) gigas McCOY lived in Middle Miocene (Balcombian) times (about 20 million years ago) in
about the same area (Victoria) as the recent Zoila (Zoila) thersites GASKOIN lives (south Australia), which is closely allied
to gigas so that the two species can be separated subgenerically at most. But while thersites becomes at most 92 mm. long
(coll. SUMMERS), the largest gigas measures 215 mm. (British Museum): it is a well preserved shell showing the total
reduction of columellar teeth as it is in Gisortia, too. In Zoila, the giant members with obsolete dentition also became
extinct, whereas the smaller, more denticulate species survived.
It will be observed, that the largest living cowry species, Macrocypraea cervus shows similar tendencies as the dying
Gisortia and Gigantocypraea though yet in a lesser degree: gigantism, wide aperture, flattened fossula, and irregularities in
columellar dentition. Possibly it may be the next living cowry to become extinct.
It was a somewhat frustrated group of adventurers that gathered at the jetty at Lumut on the first day of the Chinese New
Year. They included Jack Fisher, Stephen Chum, Alan and Mrs. Tideman and their rugged three year old son David plus two
aqualungs, ten large air cylinders, and other underwater equipment. Five days of holidays lay ahead, and now; the Captain had
orders that the boat could now only take us to Pankor Laut. Originally it was to have taken us to the Sembelans, a group of
nine islands, ten miles out beyond the Pankors and their silty water. This island we had thoroughly investigated last
November. Telephone calls to Telok Anson in Penang were in vain as all the Harbor officers were taking advantage of the long
holiday. It seemed that my 500 mile journey from Singapore, Jack and Stephen's 300 mile trip from Kuala Lumpar and Alan and
my family's 300 mile run down from Penang were to be virtually wasted, the next five days were to be spent going over ground
we had already covered without much success.
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