THE MUSEUM. 



107 



itself to the thinking mind, when 

 thousands of years it could give as it 

 were in a mere commonplace intro- 

 duction to a book — the design of which 

 was to chronicle other events — a com- 

 plete history of the creation of our 

 planet, which, up to within half a cen- 

 tury of our own time — as far as scien- 

 tific investigation is concerned — has 

 never been explained or understood. 

 • (to be continued.) 



The Unionidae or Fresh Water 

 Mussels. 



BY DR. \V. S. STRODE, LEWISTON, ILL. 



The most important and interesting 

 family of the fresh water shells is the 

 well known mussels or unionideE. Im- 

 portant because of its universal dis- 

 tribution, of the variation in size, form 

 and coloration and more particularly 

 on account of its usefulness as a scav- 

 enger and purifier of our rivers and 

 lakes. 



About 1200 species have been de- 

 scribed, over half of which belong to 

 North America. The United States 

 from the Ohio river south is particular- 

 ly rich in this branch of mollusk. The 

 Duck, Holston, Tennesee, Little Red 

 and Arkansas rivers are headquarters 

 for scores of interesting species. The 

 rivers and lakes of Florida and Texas 

 have in the last 20 years afforded more 

 new species than any other part of the 

 world. 



Nicely and systematically arranged 

 a cabinet of shells presents more di- 

 versity of form and variety and beauty 

 of coloration than can be obtained in 

 any other branch of natural history. 

 All the tints of the flowers, the grass, 

 the leaves of the trees, the changing 

 hues of the clouds and sky, the silver 

 lustre of the moon, the colors of the 



rainbow are reproduced in the splen- 

 did irridescence of the shells of sea 

 and land. 



There is hardly a stream or lake of 

 any considerable size within the Unit- 

 ed States that does not contain repre- 

 sentatives of the mussel family. 



There are about one hundred species 

 in the state of Illinois, and in the 

 classic little river, the "Spoon, " where 

 my researches have mostly been con- 

 ducted, I have found fifty of these spe- 

 ies. Some of these attain a develop- 

 ment in size, form and coloration, not 

 equalled in any other stream in the 

 world. This is due to the fact that 

 the different forms here find the envi- 

 ronment most suitable to its perfect 

 growth. 



The UnionideE must be sought for in 

 all sorts of places. Some will be found 

 only in deep, still water, others in the 

 more shallow swift running currents; 

 some prefer the soft black mud, others 

 the gravelly places; some will be found 

 only under the edges or in clefts of 

 massive rocks and others in whirlpools 

 and eddies; some species are great 

 travelers while others do not appear to 

 move from one year's end to another. 



The muskrat and mink will often 

 materially assist the collector in find- 

 ing a variety of shells. Along side an 

 old log projecting out of the water, or 

 under a snarl of roots in the bank 

 where their den is located, a great 

 quantity of shells niay be found so 

 deftly opened that they are but little 

 or not at all injured. As a rule, how- 

 ever, it is best to collect only live 

 shells from which the animal must be 

 removed and the shell thoroughly 

 washed inside and out. The valves 

 must then be tied together or closely 

 wrapped in strips of newspapers, label- 



