58. Section of the volcano of Mull along the line A B " 142 59. Summit of the volcano of Monte Sant' Angelo, in Lipari, exhibiting a crater with walls worn down by denudation 158 60. Outlines of lava-cones 160 61. Diagram illustrating the formation of parasitic cones along lines of fissure formed on the flanks of a great volcanic mountain 162 62. Outline of Etna, as seen from Catania 162 63. Outline of Etna, as seen from the Val del Bronte 163 64. Plan of the volcano forming the Island of Ischia 163 65. A primary parasitic cone, with a secondary one at its base--Ischia 164 66. Scoria-cone near Auckland, New Zealand, with a lava-current flowing from it. (_After Heaphy_) 165 67. Section of rocks below the ancient triassic volcano of Predazzo in the Tyrol 165 68. Cotopaxi, as seen from a distance of ninety miles. (_After Humboldt_) 168 69. Citlaltepetl, or the Pic d'Orizaba, in Mexico, as seen from the Forest of Xalapa. (_After Humboldt_) 169 70. Lac Paven, in the Auvergne. (_After Scrope_) 171 71. The crater-lake called Lago del Bagno, in Ischia, converted into a harbour 172 72. Lake of Gustavila, in Mexico. (_After Humboldt_) 172 73. Peak of Teneriffe, surrounded by great crater-rings. (_After Piazzi-Smyth_) 175 74. The volcano of Bourbon, rising in the midst of a crater-ring four miles in diameter. (_After Bory de St. Vincent_) 176 75. The volcano of Bourbon, as seen from another point of view, with three concentric crater-rings encircling its base. (_After Bory de St. Vincent_) 176 76. Vesuvius as seen from Sorrento, half encircled by the crater-ring of Somma 177 77. Outlines of various volcanoes illustrating the different relations of the craters to cones _to face p._ 178 78. Island thrown up In the Mediterranean Sea in July and August, 1831. (_After the Prince de Joinville_) 179 79. Sinter-cones surrounding the orifices of geysers 183 80. Diagram illustrating the mode of formation of travertine- and sinter-terraces on the sides of a hill of tuff 185 81. Map of the volcanic group of the Lipari Islands, illustrating the position of the lines of fissure upon which the volcanoes have been built up 192