REPRODUCTION AND ARTIFICIAL PROPAGATION OF FRESH-WATER MUSSELS. 1 99 



PLATE X. 



Fig. 25. Fin, as above, 36 hours after infection with glochidia of Anodonta cataracta, showing com- 

 plete overgrowth of all glochidia which have become properly attached. 



Fig. 26. Glochidium of .4. cataracta upon fin margin of carp, 3K hours after infection. Prolifera 

 lion of cyst just beginning. 



Fig. 27. Glochidia, as above, upon fin margin of carp, showing different stages of cyst proliferation, 

 even in neighboring glochidia. 



Fig. 28. Glochidia, as above, 24 hours after infection. 



Fig. 29. Hooked and bookless glochidia (.4. grandis and L. recta) embedded and developing on a 

 fin margin. 



Fig. 30. Glochidia of A. cataracta upon fin of carp, 3 days after infection, showing the cyst com- 

 pletely formed. 



Fig. 31. Glochidium of .4. cataracta upon fin of carp, developing normally after a shift of go degrees 

 from the position first taken. 



Fig. 32. Two glochidia of .4. cataracta, overgrown after 36 hours upon surface of a carp's fin. 



Fig. i3. Glochidium of .4. cataracta 35 days after infection. The metamorphosis is more advanced 

 than in figure 30 and the rudiments of the foot and other organs have assumed greater size. 



PLATE XI. 



Fig. 34. Three gill filaments of the rock bass infected with glochidia of Lampsilis ligamentina. 

 The metamorphosis of the glochidia has hardly begun, although they have been attached for 28 days. 



Fig. 35, 36, 37, and 38. Stages in the formation of the cyst sxirrounding a bookless glochidium 

 {Lampsilis ligamentina) upon a gill filament of the black bass. Taken at 15 minutes, 30 minutes, i hour, 

 and 3 hours, respectively, after infection. The transverse lines on the filaments indicate the lamella. 



Fig. 39. Anterior gill of a black bass infected with glochidia of L. ligamentina, showing distribution 

 upon the gill as a whole and the appearance of the cysts. 



Fig. 40. Gill of yellow perch, as above. 



Fig. 41. Two conglutinates of Lampsilis ligamentina removed from the marsupium. One is shown 

 from the flat surface, the other on edge. Actual length 17 mm. 



Fig. 42. Three conglutinates of Obliquaria refiexa removed from the marsupium. Actual length 

 17 mm. 



Fig. 43. Part of a gill of black bass infected with glochidia of L. ligamentina, showing the distribu- 

 tion and orientation of the glochidia in an infection above the optimum for this fish. Only the row of 

 filaments toward the observer is shown. 



PLATE XII. 



Fig. 44. Symphynota costata, dissected from fin of carp 47 days after infection. The anterior end 

 is to the left. Rudiments of foot, digestive tract, liver diverticula, and the first gill buds are recognizable ; 

 also the hooks and the degenerating adductor of Uie glochidium. Compare with figure 47. Actual size, 

 0.39 by 0.35 mm. 



Fig. 45. Strophitus edentiiliis, from a living specimen which had completed its metamorphosis 

 without parasitism and which was actively crawling about on the bottom. Seen from the ventral side. 

 The anterior and posterior adductors are well developed and within the foot the pedal ganglia and litho- 

 cysts may be seen. Two gill buds are found on either side. Sections show that the internal organiza- 

 tion is as far advanced as that of the young mussels shown in figures 47 and 48. X 106. 



Fig. 46. A single cord discharged from the marsupium of Strophitus edentulus, showing glochidia 

 extruded and others still within the cord. X13.5. 



Fig. 47. Symphynota costata, a yoimg mussel which had been crawling upon the bottom for 6 days 

 after a parasitism of 68 days. The very narrow margin of the adult shell has been drawn within the 



