FRESH-WATER MUSSELS. 



127 



Table 



-Sizes at Close oi' Second Year of Certain Mussels Reared in Ponds, Fairport 



Station, Iowa. 



Sdenti&c name. 



Common name. 



Length. 



Lampsilis ligamentina. . . 

 Lampsilis anodontoides . 



Obliquaria reflexa 



Obovaria ellipsis 



Plagiola donadformis ... 



Quadnila pjicata. 



Quadrula pustulosa . 



Quadnila imdata 



Mucketo 



Yellow sand-shell & 



Three-homed warty-back. 

 Hickory-nut 



Blue- point . . . 

 Pimple-back . 

 Pig-toe 



o other observations indicate that the mucket grows more rapidly in streams, 

 b The yellow sand-shell was only i year and 5 months 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, 1 910. 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 pustuJosa. . 



Quadrula metanevra. 



Quadrula pHcata 



Quadrula undata 



Common name. 



Niggerhead... 

 Pimple-back . 

 Monkey-face. 

 Blue-point- . . 



Pig-toe 



Length, 



Sept. 19. 



1910. 



Inches. 

 I. 92 

 J. 74 

 I. 70 

 2.80 

 I. 41 



Length, 



July 31. 



1911. 



Inches. 

 1.98 

 1.8s 

 1.86 

 3- 02 

 1.74 



Increase in 

 length. 



Inches. 



0.06 

 ■ II 

 .16 



. 23 

 •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 shown in 

 the following table (13) : 



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



Scientific name. 



Quadrula ebenus 



Quadrula pustulosa. . . . , 



Quadrula pustulata 



Quadrula metanevra 



Quadrula pUcata 



Quadrula imdata , 



Obovaria ellipsis 



Obliquaria reflexa 



Tritogonia tuberculata. , 

 Lampsilis ligamentina. . 



Lampsilis recta , 



Strophitus edentulus 



Unio gibbosus 



Common name. 



Niggerhead 



Pimple-back 



....do 



Monkey-face 



Blue- point 



Pig-toe 



Hickory-nut 



Three-horned warty-back . 



Buckhom 



Mucket 



Black sand-shell 



Squaw-foot 



Spike 



