FRESH-WATER MUSSEI.S. 



127 



Table ii. 



-Sizes at Close op Second Year op Certain Mussels Reared in Ponds, Fairport 



Station, Iowa. 



Scientific name. 



Lampsilis ligamentina. . . 

 Lampsilis anodoatoides . 



Obliquaria reflcxa 



Obotfaria ellipsis 



Plagiola donaciformis 



Quadrula pUcata , 



Quadrula pustulosa 



Quadrula undata 



Common name. 



Mucket o 



Yellow sand-shell ^ 



Three-homed warty-back. 

 Hickory-nut 



B hie-point . . . 

 Pimple-back. 

 Pig-toe 



Length. 



o Other observations indicate that the mucket grows more rapidly in streams. 

 ^ The yellow sand-shell was only i year and 3 mouths of age. 



Some medium-sized examples of several species of Quadrula were placed, after 

 measurement, in a crate which was anchored in the Mississippi River at Fairport, Sep- 

 tember 19, 1910. When the crate was recovered and the mussels remeasured, July 31 of 

 the following year, very little growth was apparent in most of the specimens. The data 

 for measurements of length in the several examples are given in the following table (12) : 



Table 12. — Increase in Length of Mussels in Cage. 



Scientific name. 



Quadrula ebenus 



Quadrula pustulosa. . 

 Quadrula metancvra. 



Quadrula phcata 



Quadrula undata 



Common name. 



Niggerhead... 

 Pimple-back . 

 Monkey-face. 

 Blue-point . . . 

 Pig-toe 



Increase in 

 length. 



Inches. 

 0.06 

 . II 

 .16 

 . 33 

 ■33 



In another experiment 76 mussels, representing 19 species, principally the thick- 

 shelled forms, were placed in a crate with nine compartments which was anchored in the 

 river about 25 feet from shore. The crate was put out July 31, 1911, and recovered No- 

 vember 14, 1913, when 36 of the original mussels, representing 13 species, were found to 

 be alive. These mussels generally manifested a higher rate of growth than marked some 

 of the mussels used in the experiment just described, although the increase in size was 

 disappointingly small. The period of time between the dates of measurements was 2 

 years 3 months and 14 days. The mussels were of medium size at the beginning of the 

 experiment, so that the growth to be expected was that which would characterize the 

 period of approaching maturity rather than that of early life. The mussels living at 

 the close of the experiment, with the maximum and minimum gain in length and the 

 average for the species (when more than two examples were available), are sho\vn in 

 the following table (13) : 



Table 13. — Growth of 36 Mussels in Crate from July 31, 1911, to Nov. 14, 1913. 



