elegant appearance.' We all thought that this description was very 

 vivid, and that it gave us a good idea of the appearance of this inter- 

 esting animal. 



Passing by several minor families of shells, Professor Parker con- 

 ducted us to a series of cases which contained a large collection of 

 Unionidce, or river mussels. These, he said, were no less interesting 

 than the marine shells which we had seen, and in many instances they 

 excelled their salt-water relatives in beauty of ornamentation. The gen- 

 eral colors were black and shades of green, and their surfaces were 

 variously marked with knobs, spines, and rib-like undulations, with 

 rays and spots of color. The tints of their interiors were most beau- 

 tiful, ranging from pure, silvery white, through orange, pink, and 

 salmon, to dark purple; and the rich, pearly iridescence rivaled that 

 of any of the marine shells. These reminded us of a collection, which 

 we had seen in the West, illustrating the pearl-button industry, and 

 from which we learned that hundreds of tons of these shells are 

 gathered yearly from the Mississippi River and sold to the button facto- 

 ries at Muscatine and other places in Iowa, for the purpose of manu- 

 facturing pearl buttons. We learned from Professor Parker that the 

 Mississippi Valley is the metropolis of this family, and that more species 

 are found there than in all the rest of the world combined. He also 

 told us that there are about one thousand different kinds of these mus- 

 sels. "Pearls," he added, "are found in river mussels, but are usually 

 of little value, although some very valuable ones have been found. 



"The shell that is the most familiar to many people is the oyster, 

 Oxtrea virginica, and in the case next to those containing the river 

 mussels, we may see a variety of these and their near relatives," 

 continued Professor Parker, walking toward a case some distance away. 

 " The cultivation of this bivalve occupies the attention of a large num- 

 ber of men, and the investment of considerable capital. The oyster 

 is free and active when young, but becomes attached to some sub- 

 merged object early in life. Oyster culturists take advantage of this 

 habit by erecting poles in the water to which the young oysters attach 

 themselves. One valve, the lower one, becomes attached, and the oyster 

 spends its life in this condition, with neither foot nor siphon, and 

 entirely dependent upon the currents in the surrounding water for its 

 food, which consists of the larvae of sponges and mollusks, and of various 

 species of microscopic animals. The oyster has many enemies, chief among 

 which is a species of boring sponge, which eats into the valves to such 

 an extent that it falls to pieces. Another enemy is the drill, which 

 bores a hole in the shell and sucks the juices of the animal through 



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