LIST OF PLATES AND TEXT FIGURES. 



Plate I. 



Fig. 1. Herring' scale on a dark background: the winter rings appear darker than 

 the summer zones. xl4. (Lea phot.) 



Plate IT. 



Fig. 2. Herring scale on light background: the winter rings appear brighter than the 

 the summer zones. xl4. (Lea phot.) 



Plate HI. 



Fig. 3. Left half: Impression in a collodion film of surface of portion of a herring 

 scale. Right half: Same portion of the actual scale itself. xl5. 



Fig. 4. Scale split, the detached part showing a contour similar to that of the whole 

 scale; pattern formed by fibrils on the surface of distension. x9. 



(Lea phot.) 



Plate IV. 



Fig. 6. Part of herring scale, the outer covering removed, showing margins of 

 fibrillar plates with alternating tangential and radial course of the 

 fibrils. x75. (Lea phot.) 



Fig. S. Part of cross-section through a herring scale, stained with thionine. x380. 



(Lea phot.) 



Fig. 13. Effect of silver impregnation acting from the outer surface of a scale. xl70. 



(Lea phot.) 

 Plvi'eV. 



Fig. 14. Total views of a herring scale, impregnated with silver, demonstrating the 

 inner system of annual zones. Oblique illumination. xl3. 



Fig. 15. Half of a scale with normal structure. xl7. 



Fig. 16. Half of a scale with abnormal structure from the same herring as the scale 

 shown in Fig. 15. xl7. (Lea phot.) 



Plate VL 



Fig. 17. Part of an abnormal scale, the outer covering layer of which is removed, 

 showing irregular course of fibrils. xl()7. Compare with fig. 6, Plate IV. 



!Pig. 18. a. b. c, d. The appearance of scales situated near an abnormal one. Central 

 portion of four scales shown, taken in successive order from a lateral 

 scale-row : 



a. Ninth scale in the row being normal, 



h. Tenth scale in the row being slightly modified, 



c. Eleventh scale, being greatly modified, 



d. Twelfth scale is abnormal. The next scales in the row (on the other side 



of the abnormal one) show similar feature^. 



Fig. 23. Pa't of a scale, showing faint concentric shadows, caused by the inner 

 fibiilbar plates (corresponding to Fig. 14, Plate V). x9. (Lea phol.) 



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