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 sea-tortoise," as our author puts it, but he goes on to describe a "mountain-tortoise, the largest and with the thickest shell," which may be Chelone mydas, the "green turtle" (also a sea-tortoise), but is more likely one of the gigantic land-tortoises (family Testudinidae) which appear in many of the islands of the Western Indian Ocean; of which most are now extinct, (Testudo grandidieri only recently in Madagascar), while others, like T. gigantea and T. daudini, are still found in less frequented islands. The "land-tortoise" and the "white-tortoise" may include several species of Cinyxis, Pyxis and Testudo.

(See Cambridge Natural History, VIII, 364–387.)

30. Cinnabar, that called Indian.—(Dragon's blood.) The confusion between dragon's blood (the exudation of a dracaena) and our cinnabar (red sulphide of mercury) is of long standing, but less absurd than it seems at first sight. The story is given in Pliny (XXXIII, 38, and VIII, 12). The word kinnabari, he says, is properly the name given to the thick matter which issues from the dragon when crushed beneath the weight of the dying elephant, mixed with the blood of either animal. The occasions were the continual combats which were believed to take place between the two. The dragon was said to have a passion for elephant's blood; he twined himself around the elephant's trunk, fixed his teeth behind the ear, and drained all the blood at a draught; when the elephant fell dead to the ground, in his fall crushing the now intoxicated dragon. Any thick red earth was thus attributed to such combats, and given the name kinnabari. Originally red ochre (peroxide of iron), was probably the principal earth so named. Later the Spanish quicksilver earth (red sulphide of mercury), was given the same name and preferred as a pigment to the iron. Later, again, the exudations of Dracaena cinnabari in Socotra and Dracaena schizantha in Somaliland and Hadramaut (order Dracaeneae), and Calamus draco in India (order Palmeae), were given the name kinnabari. Being of similar texture and appearance, the confusion is not surprising, as the Romans had no knowledge of chemistry.

Pliny noted errors made by physicians of his day, of prescribing the poisonous Spanish cinnabar instead of the Indian; and proposed a solution of the problem by calling the mercury earth minium, the ochre miltos, and the vegetable product kinnabari, but usage did not follow him. We now give the mercury earth the old Greek name for dragon's blood, and the dried juice we give the same name in English.

Wellsted (Travels in Arabia, 1838, II, 450–1) noted the two varieties of Dracaena, one of which had leaves the camels could eat,