FRESH WATER CLAMS. 
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The naiades, or pearly fresh-water mussels, have a distribution through- 
out the lakes and waters of the globe, not only on the continents, but also 
on all the larger and some of the smaller islands. They exist in countless 
numbers, especially in the United States, which seems to be the metropolis 
of these forms, both as to species and individuals. Probably over 600 valid 
species are now living in North America, and fully three-fourths of these 
are found in the Mississippi drainage area and the streams which fall into 
the Gulf of Mexico from the north. Many of these mussels here attain great 
size. Some are covered with knobs or postules, or have peculiar and strik- 
ing forms, while others are brilliant with radiating stripes or beautiful 
and intricate patterns or coloring. The interiors of many of these species 
are very rich, the colors varying from almost blackish-purple to coppery, 
glowing red, pink, straw-color and silvery white. 
Within the past few years a great deal of interest has been aroused in 
the United States in regard to these mussels. Thousands of persons have 
given more or less attention to hunting them for their pearls, which often 
have a high money value, and others have gone quite extensively into the 
business of manufacturing the shells into buttons and various ornaments. 
So great has been the drain on them that in many places they have become 
very scarce and are even threatened with extinction. 
The number of young contained in the female of the naiades at a single 
time is often very great. Many of them probably contain from 500 to 1,000 
at a time, if fully adult. In other species inhabiting the waters of Lake 
Nicaragua, Central America, the female sometimes carries no less than 
6,000,000 young. 
There is ample need for all these young, for from the time of their birth 
until they die of old age, they are constantly beset by enemies and forces 
that cause their destruction. Even nature herself seems bent on destroying 
them. During a severe winter, thousands are destroyed by the cold. In 
summer other millions are killed by the drying up of streams, the pollution 
of the water supply and other causes. 
Hogs are a great enemy to the naiades, and they not only destroy such as 
are found on the surface, but root them out from almost any depth. The 
dumping of manufactories and the sewage of cities turned into rivers are 
destroying not only the fish but the naiades. 
The immense number of mussels taken by pearl-hunters and the manufac- 
turers of buttons and ornaments, generally in the most wanton way, is 
undoubtedly diminishing the supply with great rapidity. In cases where 
individuals are collecting independently, either for pearls or to sell to man- 
ufacturers, it would probably be very difficult to get them to even throw 
the small mussels back into the water. But manufacturers who ought to 
be wise enough to understand how rapidly the supply is being exhausted 
and how much it is to their interest to preserve it, might at least use their 
infiuence to have those in their employ attend to this matter. No mussel 
less than four or five years old should be taken by a pearl-hunter, or any- 
