LIST OF ILLUSTRATIONS. 



PAGE 

 Frontispiece. 



FIG. 1 A. Common Roach ; B. An. Outline figure 



of the Burbot (Lota vulgaris) . . 12 



,, 2 Diagrammatic figure of an Eel . . 13 



,, 3 Head of a young Polypterus ... 26 



4 The Evolution of Teeth and Scales . 40 



5 Skull of Dog-fish . . . . 47 



6 The Evolution of the Fish's Tail . . 52 



,, 7 The Evolution of Fins .... 66 



,, 8 Head of Gnathonemus elephas . . 90 



,, 9 Ohiasmodon niger ..... 95 



,, 10 Sticklebacks and Nest .... 102 



11 A Larval Dog-fish 127 



,, 12 Fish Metamorphoses (three stages in the 



life history of the Eel) . . .132 



,, 13 Three stages in the development of the 



Sword-fish 135 



., 14 Outline figure of the American Mud-fish 151 



,, 15 Restoration of a Primitive Sturgeon . 178 



,, 16 Three extinct Ancestral Forms of Fishes 199 



, 17 Three Primitive Sharks 203 



