REPRODUCTION AND ARTIFICIAL PROPAGATION OF FRESH-WATER MUSSELS. 20I 



Figs. 62-63. Transverse sections of glochidia of Lampsilis ligamentina, taken 30 minutes and 3 

 hours, respectively, after attachment to gill filament. In 62 the development of cyst has made con- 

 siderable progress, while in 63 the cyst wall is practically completed. In 62 several mitotic figures 

 are seen in the epidermis where multiplication of cells is taking place. 



Fig. 64. Highly magnified section of a portion of the glandular epithelium of an interlamellar 

 junction in the gravid marsupium of Quadrula ehena, showing the large mucus cells and the nuclei of 

 several leucocytes (1) with which the epithelium has become infiltrated. 



PLATE XVI. 



Fig, 65. Station of the Bureau of Fisheries at North La Crosse, Wis., and steamer Curlew, used 

 in mussel investigations during summer of 1908. 



Fig. 66. Interior of station at North La Crosse, equipped as a laboratory. 



Fig. 67. Seining young black bass near La Crosse in a "lake" which had been filled by the over- 

 flow of the Mississippi River during the early summer. The fish thus obtained were artificially infected 

 with glochidia. 



PLATE XVII. 



Fig. 68. Dredging for young mussels in a slough near La Crosse. 



Fig, 6g, The clamming outfit used in the mussel work on the Upper Mississippi River. The two 

 "crow-foot" dredges, with the mussels still clinging to the hooks just after a haul, are seen resting on 

 the stanchions. 



Fig. 70. An old mussel bed near Muscatine, Iowa, btu'ied under a foot or more of sand and mud 

 but exposed in cross section by a gully washed out by rains. The mussels are seen in silu embedded 

 in the wall of the gully. 



