The reported northern distribution limit of G. demissa is Prince Edward
Island in Canada (in fact, I think this may be its type locality), and
this species is very common in the New England coast.
Of course G. demissa has also been introduced into the west coast, having
become a dominant member of the community in San Francisco Bay, and other
locales.

Francisco.

On 7/30/15 11:36 AM, "Conchologists List on behalf of Harry Lee"
<[log in to unmask] on behalf of [log in to unmask]> wrote:

>I don't recall hearing anything substantive on the matter for about
>six years: 
><https://listserv.uga.edu/cgi-bin/wa?A2=ind0910B&L=CONCH-L&P=R413&X=A36E28
>8A086962535B&Y=shells%40hglee.com>.
>
>Harry
>
>
>At 11:04 AM 7/30/2015, Derrick Hudson wrote:
>>Hello,
>>
>>     I know this is a very old string, but I'm new to CONCH-L and am
>> catching up. The paper
>>Genetics and taxonomy of ribbed mussels (Geukensia spp.), By Sarver
>>et al. 1992 addresses this question fully. As for my experience I
>>believe that G.demissa is the East coast species that spans from
>>Rhode Isaland [sic] to South Florida and that G.granosissma [sic] is
>>the Gulf of Mexico species. I personally have not found any
>>G.demissa North of the Keys.
>>
>>Derrick
>>
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