The spherical greenstone in the mountain district of Guanaxuato is perfectly similar to that of the Fichtelberg in Franconia. Both form grotesque domes, which break through and are superimposed on transition argillaceous schists. In the same manner pearl-stone, porphyritic schist, trachyte, and pitch-stone porphyry present analogous forms in the Mexican mountains, near Cinapecuaro and Moran, in Hungary, Bohemia, and in Northern Asia. Footnote 82: p. 220—“_The Colossal Dragon-tree of Orotava_.” This colossal dragon-tree (Dracæna draco) stands in the garden of M. Franqui, in the little town of Orotava, called formerly Taoro, one of the most charming spots in the world. In June, 1799, when we ascended the Peak of Teneriffe, we found that this enormous tree measured 48 feet in circumference. Our measurement was made at several feet above the root. Nearer to the ground Le Dru found it nearly 79 feet. Sir G. Staunton asserts that at an elevation of ten feet from the ground, its diameter is still 12 feet. The height of the tree is not much more than 69 feet. According to tradition it would appear that this tree was venerated by the Guanches (as was the ash-tree of Ephesus by the Greeks, the Plantain of Lydia, which Xerxes decorated with ornaments, also the sacred Banyan-tree of Ceylon), and that in the year 1402, which was the period of Béthencourt’s first expedition, it was as large and as hollow as in the present day. When it is remembered that the dragon-tree is everywhere of very slow growth, we may conclude that the one at Orotava is of extreme antiquity. Berthollet says, in his description of Teneriffe, “On comparing the young dragon-trees which grows near this colossal tree, the calculations we are led to make on the age of the latter strike the mind with astonishment.”[LY] The Dragon-tree has been cultivated from the most ancient times in the Canary isles, in Madeira, and Porto Santo, and that accurate observer, Leopold von Buch, found it growing wild near Iguesti in Teneriffe. Its original habitat is not therefore the East Indies, as has long been believed; and its appearance does not afford any refutation of the opinion of those who regard the Guanches as a wholly isolated primitive Atlantic race, having no intercourse with African or Asiatic nations: The form of the _Dracænæ_ is repeated on the southern extremity of Africa, in the Isle of Bourbon, in China, and in New Zealand. In these remotely distant regions we recognise species of the same genus, but none are to be found in the New Continent, where this form is supplied by the Yucca. The _Dracæna borealis_ of Aiton is a true _Convallaria_, the nature of both being perfectly identical.[LZ]