FRESH-WATER MUSSEI^S AND MUSSEly INDUSTRIES. 



21 



the hinder portion of the shell constitute the shiny backs, as they were originally called, 

 or iridescents, as they are now more generally termed. The iridescents are of exceptional 

 quality and command a substantial premium in the market, where they rival the high- 

 priced buttons made from so-called "ocean pearl," or the shells of certain marine 

 mollusks. While it is usually customary to finish the face of the blank which corre- 

 sponds to the inner surface of the shell, a better product is obtained with iridescent 

 buttons if the face corresponding to the outer surface, or back, of the shell be finished 

 to make the face of the button. 



There is some difficulty not only in keeping the two sorts of blanks separate, but 

 also in insuring that the blanks are cut entirely from the iridescent portion instead of 

 partly from the iridescent and partly from the lustrous white surface. Since compara- 

 tively few are obtained in any case, it is not a' general practice to cut for iridescents, 

 and most of the iridescents of commerce are cut and finished by chance, as it were, 

 and simply sorted out in the process of grading the finished buttons. A prominent 

 manufacturer stated at one time that a much higher price could be obtained for irides- 

 cents if one could obtain a sufficient number upon which to build a line of trade. As 

 it is, iridescents are generally an incidental product. 



As compared with shells like the Lake Pepin mucket, or the ordinary river mucket, 

 there is considerably more waste in niggerheads, on account of the heavy hinge and 

 teeth and the relative differences of thickness between the forward and hinder parts of 

 the shell. For this reason particularly, relatively small niggerhead shells, from 1.5 to 

 2.5 inches in greatest dimension, are preferred. Such are the shells taken in the Missis- 

 sippi about Le Claire, Iowa, and in the White and St. Francis Rivers of Arkansas. In 

 the early years of mussel fishery in any niggerhead stream, a large proportion of heavy, 

 coarse shells were taken, and they w^ere much less desirable. Owing to the generally 

 depleted condition of most niggerhead beds, few large shells are now taken, but occasional 

 specimens are found that are upward of 4 inches in length. Some of these are of excellent 

 quality, but there is a great deal of waste in cutting them, as most of the blanks are very 

 thick and have to be ground to the desired degree of thinness for buttons. 



The relative economy in use of niggerhead mussels of different sizes is shown b}^ 

 the following record of tests as to number of blanks per shell and per ton : 



Sizes, Weights, and Button Production for Niggerhead Shells (Approximate Figures). 



Longest dimension. 



Niunber 



of mussels 



per ton. 



18-line 



blanks 



per single 



shell. 



Quantity 

 of blanks 

 per ton. 



Greater 

 than — 



I*ess than — 



Inches. 



I 



2 



23^ 



23^ 



3 



4 



Inchest 



I 



iK 



ly. 

 2K 



3 



3M 



4 



174,000 



110,000 



55,000 



33 > 000 



26,000 



20,000 



15,000 



10, 500 



8,500 



6, 200 



4,000 



3,200 





Gross. 











1-2 



3 



4 



S 



7 



08 



a 10 



a 12 



014 



688 



1,083 



I, III 



1,042 



1,021 



944 



868 



667 



622 





« At the titae of making this table only a few of the larger-sized shells were available, so that the estimates of blanks 

 are less accurate for these sizes. 



