Dear Geoff and others,
I would very much like to learn of any reports such as this in the
literature. My meager knowledge is based on only two "experiments,"
actual counts of kilograms/many thousands of specimens of shells, and
another educated estimate.
Taking all comers (freshwater and marine snails as well) the measured
frequency of reverse coiling ranges from 1:440 for Prunum apicinum
from Long Is., Bahamas (Lee, 1979) and 1:760 for Hyalina
philippinarum (Coovert and Lee, 1989). On the other end of the
spectrum perhaps is the Sacred Chank of India (Turbinella pyrum),
which is quite abundant and used in commerce. A Brit by the name of
Hornell (1916) observed the fishery for a long period and ultimately
calculated 1:600,000 as the frequency of the reversed (sinistral)
mutant. It is a fact that, although there are many gastropods that
may be collected by the millions, the majority of them have never
been reported in the reversed-coil motif. Other than the three papers
I cite, I know of no other systematic report on this frequency.
Coovert, G. A. and H. G. Lee, 1989, A review of sinistrality in the
family Marginellidae. Marginella Marginalia 6(1,2): 1-15.
Hornell, J. 1916. The Indian varieties and races of the genus
Turbinella. Mem. Ind. Mus. 6:109-125, 3 pls.
Lee, H. G., 1979 Letters to the editor [on sinistral marginellids].
The Mollusk, Greater Miami Shell Club 17(1):2 incl. 2 text figs. Jan.
Harry
At 01:22 AM 7/16/2006, you wrote:
>Dan,
>Like Harry, I too have stripped the garden searching for these sinistral
>shells but to no avail.
>I have only seen one specimen collected locally in Melbourne.
>The only quoted incidence I can remember is an old book ?Dance at 1 in 10000
>Regards
>Geoff
>
>
>>From: Dan Yoshimoto <[log in to unmask]>
>>Reply-To: Conchologists List <[log in to unmask]>
>>To: [log in to unmask]
>>Subject: Sinistral Cornu aspersa (Helix aspersa)
>>Date: Sat, 15 Jul 2006 11:12:02 -0700
>>
>>Dear ALL,
>> As today is kinda slow, I thought that I might get some
>>information
>>on the sinistrality of helix aspersa. The other day I had a friend drop by
>>with a beautiful, live adult specimen that he took from his garden. He
>>said that he generally tosses hundreds of Helix aspersa (Cornu aspersa)
>>from the garden but this one caught his eye. I photographed his specimen,
>>but he asked if this was an unusual or rare occuranace. So, here I am
>>again, asking for some "opinions" on the rarity of this specimen.
>>Dan
>>
>>Dan, Hiromi & Kuma Yoshimoto
>>Eureka, California
>>U.S.A.
Harry G. Lee, M. D.
4132 Ortega Forest Dr.
Jacksonville, FL 32210 USA
voice (904) 389 4049
email: [log in to unmask]
look at www.jaxshells.org
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