Cecil and all,
I have compared the image of Burgess's COWRIES OF THE WORLD -Cyp. cassiaui- with
those on your site, and the commercial site given below, and the question has
to be, "How much encroachment into the sulcus is sufficient to complete the
offense?" All three of your shells, as well as the "cassiaui" at the link
below, show pustular imposition into the sulcus, IMHO.
Partly, it is testament to the high quality of 21st century imaging, yours and
the commercial site's. But,... if anyone would know what a representative
specimen of -Cypraea cassiaui- should look like, it had to be Burgess! His
image of -cassiaui- is small and not available for enlargement.
The apertures of the suspect shells show the plain front-to-back curve of a
-nucleus- whereas Burgess's image shows an aperture which bends in the
mid-section but is rather straight at its ends. Additionally, the -nucleus-
(top view) shape becomes narrower more rapidly, on its columellar side, toward
the anterior end while the -cassiaui- remains broader, tapering more
consistently toward the anterior on both sides. But, it isn't that simple...
I found another image of a -cassiaui- in the HSN (at
http://cowrys.org/archive/NSN396CY.HTM) which shows a wide-margined shell with
a sharp, clearly-defined sulcus. Its top-view shape, however, invokes thoughts
of -granulata-. Soooo,...
There doesn't seem (as usual) to be a clear answer about what is a -nucleus- or
a -cassiaui- or a -granulata-. It pretty much depends on who makes the
judgement,... and who wants to believe it.
Aloha,
Bob Dayle
++++++++++++++++++++++++++++++++++++++++++++++
Quoting Cecil Bankston <[log in to unmask]>:
> Thanks for all the replies. I was influenced by the prominent dorsal sulcus
> with no encroachment by the granulations in the middle and right specimens I
> posted on my web page. That feature is supposed to be a differentiating
> criterion for cassiaui.
>
> Some of the pictures of "cassiaui" on the web also appear almost identical to
> 2 of my specimens, e.g.,
>
http://www.perlae.fr/price_list/cypraeidae/cypraea_granulata_cassiaui_18_2/3.htm
> A Google search will yield several similar images.
>
> Are those specimens probably misidentified?
>
> Do all cassiaui have the violet color, or are there color variants, as some
> of the pictures on the web would seem to imply? Do all cassiaui have the
> same absence of gloss that granulata shows?
>
> Cecil Bankston
>
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