57. Remarkable facts connected with pearls—their nature 436 58. Instances of the use of pearls 437 59. How pearls first came into use at Rome 440 60. The nature of the murex and the purple 441 61. The different kinds of purples 443 62. How wools are dyed with the juices of the purple 445 63. When purple was first used at Rome; when the laticlave vestment and the prætexta were first worn 447 64. Fabrics called conchyliated 448 65. The amethyst, the Tyrian, the hysginian, and the crimson tints 449 66. The pinna, and the pinnotheres 450 67. The sensitiveness of water-animals; the torpedo, the pastinaca, the scolopendra, the glanis, and the ram-fish 451 68. Bodies which have a third nature, that of the animal and vegetable combined—the sea-nettle 453 69. Sponges; the various kinds of them, and where they are produced: proofs that they are gifted with life by nature 454 70. Dog-fish 456 71. Fishes which are enclosed in a stony shell—sea-animals which have no sensation—other animals which live in the mud 458 72. Venomous sea-animals 459 73. The maladies of fishes 460 74. The generation of fishes 461 75. Fishes which are both oviparous and viviparous 465 76. Fishes the belly of which opens in spawning, and then closes again 466 77. Fishes which have a womb; those which impregnate themselves _ib._ 78. The longest lives known amongst fishes 467 79. The first person that formed artificial oyster-beds _ib._ 80. Who was the first inventor of preserves for other fish 469 81. Who invented preserves for murenæ _ib._ 82. Who invented preserves for sea-snails 470 83. Land-fishes 471 84. The mice of the Nile 472 85. How the fish called the anthias is taken 473 86. Sea-stars 474 87. The marvellous properties of the dactylus 475 88. The antipathies and sympathies that exist between aquatic animals _ib._ BOOK X.