Kurt, Gary, I knew I could count on you. Thanks also to Tom Watters for an informative reply. I guess the ball's back in my court. About Muscle Shoals (which is on the Tennessee River in northern Alabama): The words "mussel" and "muscle" have the same derivation; originally, they were the same word, spelled differently and given different meanings. The original meaning in Latin is "little mouse"! In the case of the muscle, this may represent a fossilized Roman joke: "Here, kids, watch the little mouse run up and down my arm." In the case of the mussel, I think our forebears were at a loss for words. Muscle Shoals was a long stretch of the Tennessee River that was broken up into many channels by limestone bedrock. It was named for the mussels that formerly lived there in great abundance. The name is a translation of Cherokee Dagunahi, "mussel place" (daguna = mussel, -hi = place). They also called it Chustanaluyi, "shoals place". In English, the name was spelled either as Mussel Shoals or as Muscle Shoals until the U.S. Board on Geographic Names standardized it as Muscle Shoals in 1892. The standardized and obsolete spelling has led to a local legend that Muscle Shoals was named "because you had to use a lot of muscle to push your way through the shoals." Collector Herbert H. Smith tried hard to reform the spelling in the early 1900's, partly to publicize the environmental disaster that was going to happen when the Tennessee River was dammed, but few people followed his example. The environment has changed from one of rushing water to one of still water, wiping it out as a desirable habitat for most species of mussels. The Coosa River is another river in Alabama that runs over limestone (and dolomite, a similar rock) over much of its course. The river water is therefore rich in dissolved calcium carbonate, which the mussels need to build their shells and to keep them from dissolving back into the water. The Coosa flows into the Alabama River, not the Tennessee, and this river system has its own huge diversity of mussels and freshwater snails. In its natural state, the Coosa River consisted of a series of rapids and pools, and each set of rapids had its own fauna of snails. Thirteen species of Gyrotoma, the entire genus, were made extinct when virtually the entire river was dammed, converting it into a series of lakes for the purpose of power generation. Herbert and Daisy Smith were on the scene in the early 1900's, collecting snails from shoals as the lake water literally rose at their feet. Imagine how that felt. The last dams were erected in the 1960's, just before the passage of laws that would have protected the snails. The part of the original fauna that throve in deep pools is doing very well in the new lakes, but the part that required fast-flowing water is now restricted to a few tributaries and other areas. Occasionally a species thought to be extinct, such as the big freshwater snail Tulatoma magnifica, is found living in some tiny area, but their situation is precarious. A single chemical spill or other unexpected environmental change could wipe these diminished species out altogether. So Alabama had (and still has) extraordinary diversity in its freshwater molluscan fauna, but it also has the highest rate of extinction among them in the United States. Abrazo, Andrew Andrew K. Rindsberg Geological Survey of Alabama