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Troca bead
1. There is no population in which only rostrate or melanistic shells occur, and normal shells are absent.
2. There is locally a gradual passing from normal shells to sub-rostrate and rostrate ones; Cernohorsky estimated (by letter)
the relative frequency of these stages in Mauritia eglantina Duclos in Mondoure Bay as about 30: 5: 1.
3. Rostration and melanism often occur in the same specimen, but they are not always linked.
4. Localities from which such shells are known, may be scattered over the whole region inhabited by the species, but they
evidently are concentrated in certain smaller areas.
5. The tendency to become rostrate or melanistic differs, as certain species seem not to be susceptible at all or at least
less susceptible to rostration and melanism than other species.
There seems to be no predominance of any sex in rostrate cowries; the radula evidently does not differ from that of normal
specimens.
Certain specific names are persistently used in literature, despite their invalidation by the I.C.Z.N. some 10 years ago. As
I was one of the culprits in using two invalid names in my Catalogue of Living Cypraeidae, I thought it advisable to make the
necessary corrections.
By opinion 261 (published 10th August, 1954), the work of L. T. Gronovius, Zoophylacium Gronovianum, 3 parts, 1763 - 1781,
and F. C. Meuschen's Index to Gronovius' work from 1781, have been rejected as non-binominal. This will invalidate the
following names:
The following names should be treated as synonyms: amabilis Jousseaume 1881 = walkeri; merista Iredale 1939 = continens;
barbara Kenyon 1902 and rossiteri Dautzenberg 1903 = bregeriana. The juvenile Ipserronea problematica Iredale 1935 surely
does not belong to walkeri (as Allan 1956, Cowry Shells p. 49 suggested), but to Erronea pyriformis Gray 1824 (see Iredale
1939, Austr. Zoologist 9:317).
In these years after World War II, many interesting cowries have been collected, and much new information became known to us,
also concerning walkeri, so that we were obliged to revise our views, both with regard to taxonomy and distribution.
Taxonomy: The East Australian continens cannot be separated from the Malayan surabajensis; but there seems also to be no
constant character of the Lemurian walkeri, though the latter seems to be generally smaller, paler, and less zonate than the
Malayan "race'' (which should be called continens by law of priority). Whereas the Philippine shells from Siassi Is. are
usually very large (30 to 35 mm.) and dark (dorsal zone vividly brown, well marked, aperture purple throughout), a population
from Ubey on Bohol Is. (destroyed in the museum of Hamburg, one shell No. 3120 in my collection excepted) recalls the
Lemurian shells in size (17 to 25 mm.) and color (creme, zones obsolete, interstices of columellar teeth only pale purplish).
Therefore all specimens from Lemuria to the Philippines and Queensland should be called walkeri. However, the New Caledonian
race bregeriana has proved to be of almost specific rank, and is characterized by tiny opaque white specks embedded into the
glossy orange base and margins, like no other cowry species, Chelycypraea testudinaria Linnaeus excepted: these white specks
are never absent in well preserved bregeriana (though overlooked by its author!), and generally are recognizable in beach
shells too; but they have never been observed in any walkeri coming from farther west than New Caledonia (Joanett Is.
excepted, see below).
Distribution: The areas from which walkeri has been known to the writer till 1941 have been marked by black circles (walkeri)
and triangles (bregeriana) in the map: The three races of walkeri mentioned above seem to be separated by zones uninhabited
by the species. However, after World War II many new localities became known to us which fill up these gaps, or extend the
limits in northern, eastern, and southern direction. Therefore the following areas should be added, which have been marked,
on the map, by empty circles and triangles respectively:
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