ILLUSTRATIONS xxix 



FIG. PAGE 



54. Deep-sea fishes — extremes of adaptation in locomotion and illumina- 



tion 173 



55. Phosphorescent illuminating organs of deep-sea fishes 174 



56. Map — North America in Upper Devonian time 175 



57. The earliest known limbed animal 176 



58. A primitive amphibian 177 



59. Descent of the Amphibia 178 



60. Chief amphibian types of the Carboniferous 179 



61. Skull and vertebral column of Diplocaidiis 180 



62. Map — the world in Earliest Permian time 181 



63. Amphibia of the American Permo-Carboniferous 182 



64. Skeleton of Eryops 183 



65. JNIap — the world in Earliest Permian time 185 



66. Ancestral reptilian types 186 



67. Reptiles with skulls transitional from the amphibian 187 



68. ]Map — the w^orld in Middle Permian time 188 



69. The fin-back Permian reptiles 189 



70. Mammal-like reptiles of South Africa 190 



71. A South African "dog-toothed" reptile 192 



72. Adaptive radiation of the Reptilia 193 



73. Geologic records of reptilian evolution 195 



74. Dinosaur mummy — a relic of flood-plain conditions 197 



75. Reptiles leaving a terrestrial for an aquatic habitat 199 



76. Convergent adaptation of amphibians and reptiles 200 



77. Adaptation of reptiles to the aquatic habitat zones 201 



78. Alternating adaptation of the "leatherback" turtles 202 



79. The existing "leatherback" turtle 202 



80. Marine adaptation of terrestrial Chelonia 203 



81. Marine pelagic adaptation of the ichthyosaurs 204 



82. Restorations of two ichthyosaurs 205 



