Conch-L'ers,
 
To the references made earlier on abnormally-reversed Conus species, let me
add that I have sinistral specimens of tghe following cones in my collection:
 
Conus anabathrum Crosse, 1865
Conus baccatus Sowerby, 1877
Conus furvus Reeve, 1843
Conus infrenatus Reeve, 1848
Conus tinianus Hwass, 1792
Conus ventricosus Gmelin, 1791
 
I hasten to add, splitting or lumping notwithstanding, Contraconus seems to
be a monophyletic enterprise, and, regardless of how many trivial taxa
derived, it was a lineage which prospered but lived only a few million years
- a trice geologically.
 
Harry
 
 
At 06:27 PM 1/15/99 -0700, you wrote:
>Ross,
>
>1.  I just happened to be looking at Petuch's "Atlas of Florida Shells"
>the other night and noticed the comment, "Along with C. heilprini, C.
>mitchellorum was probably the last-living left-handed cone"(p. 361).
>Unfortunately, he does not give stratigraphic details beyond "Pliocene
>and Pleistocene" in the subtitle of the Atlas.
>
>While I don't agree with a lot of Petuch's species, and he has surely
>over-split the subgenus Contraconus, as well, I cannot believe from his
>plates that they are _all_ adversarius.
>
>2.  Along with ventricosus, a few other species of cone have been found
>as sinistral freaks.  There is a picture of a sinistral furvus (claimed
>to be truly sinistral and not a printing error) obtained by A.J. da
>Motta at Hawaiian Shell News 29(7):5.  The picture has an awkward look
>that is more abnormal than would be expected from simply reversing the
>plates.
>
>I have seen occasional references to the finding of sinistral specimens
>in other species of cone, but don't have them readily at hand.
>
>3.  Regarding the inheritance of handedness, I recall from my college
>genetics class that a sinistral population of Lymnaea stagnalis was
>found in Europe and bred with normal dextral snails to determine the
>genetics.  The reason this was important is that the handedness of an
>individual depended not on _its_ genes, but the genes of its _mother_!
>This comes about because, in molluscs, as in some other inverts, the
>fate of the embryonic shells is determined at the very first division,
>i.e., one of the two daughters is destined to form half "A" of the final
>animal, while the other daughter forms half "B."  If you separate the
>two daughter cells at this stage, and could raise them both out, you
>would get two half-snails.  (This is in contrast to vertebrates,
>echinoderms, and some other things, where the fate of the daughter cells
>is not fixed until several divisions later.)  Anyway, the direction of
>that first division is determined by a cellular structure called the
>centriole.  Since spermatozoa contribute little more than the nucleus to
>the embryo, the centrioles must, of necessity come from the mother,
>hence the strange pattern of inheritance.
>
>Bruce Neville
>Albuquerque, NM
>[log in to unmask] or [log in to unmask]
>
Harry G. Lee
mailto:[log in to unmask]
Suite 500, 1801 Barrs Street
Jacksonville, FL  32204
U. S. A.    904-384-6419
Visit the Jacksonville Shell Club Home Page at:
http://home.sprynet.com/sprynet/wfrank/jacksonv.htm
 
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