Pearls 153 XII. The Nature of the Murex and the Purple 160 XIII. Bodies which have a Third Nature, that of the Animal and Vegetable Combined 164 XIV. The Shark 165 XV. Oyster-Beds, and Fish-Preserves 167 XVI. Land-Fishes 169 XVII. How the Fish Called the Anthias is Taken 170 XVIII. The Echeneis and the Torpedo 172 XIX. The Instincts and Peculiarities of Fishes 174 XX. Coral 176 XXI. The Various Kinds of Oysters 177 _BOOK VII._ THE NATURAL HISTORY OF BIRDS. I. The Ostrich 180 II. The Phœnix 181 III. The Eagle 182 IV. The Vulture and the Hawk 187 V. The Crow, the Raven, and the Owl 191 VI. The Woodpecker of Mars 193 VII. The Peacock and the Rooster 194 VIII. The Goose 197 IX. Cranes 198 X. Storks and Swans 199 XI. Foreign Birds which Visit Us 201 XII. Swallows 203 XIII. Birds which take their Departure from Us in Winter 204 XIV. The Nightingale 206 XV. The Halcyons: the Halcyon Days that are Favorable to Navigation 208 XVI. The Instinctive Cleverness Displayed by Birds in the Construction of their Nests 209 XVII. The Acanthyllis and the Partridge 210 XVIII. Pigeons 213 XIX. Different Modes of Flight and Progression in Birds 215 XX. Strange and Fabulous Birds 216 XXI. The Art of Cramming Poultry.—Aviaries 224 XXII. Peculiarities of Animals 226 _BOOK VIII._ THE VARIOUS KINDS OF INSECTS. I. The Extreme Smallness of Insects 232 II. Whether Insects Breathe, and Whether they have Blood 234 III. Bees 236 IV.