The Indians of Brazil prize the so-called Amazon stones (jade) more highly than any other of the ornaments they wear. This is not chiefly because of their ornamental quality, but rather because these _ita ybymbae_ (green stones) have in many cases been handed down from generation to generation for many centuries. They are of cylindrical, tabular or other regular form and polished, and are believed to be amulets affording protection against many diseases as well as against snake bites. They are worn suspended from the neck and are regarded as valuable aids in difficult parturition. Because of their remedial virtues they are sometimes called _ita poçanga_, or “medicine stones.” They are also found with the natives of the Caribbean islands and are there called “the smooth stones from the far-off continent.”[284] As in all superstitions, so in those concerning jade in China, the fact that ill luck instead of good luck fortuitously resulted from the use of the material was explained in a way that did not do violence to the fundamental idea. We are told that on the road near Kneha, in Turkestan, there lies a block of jade from the quarries of Raskam-Darya, in Eastern Turkestan. This block was on its way to Peking, when orders came from the imperial court not to forward any more jade from this quarry. The reason was that the heir apparent had been taken ill after having slept on a couch made of Raskam jade.[285] Jasper In the collection of the Biblioteca di Ravenna there is a red jasper amulet engraved with a device representing Hercules strangling the Nemæan Lion. Amulets of this type are recommended for the cure of the colic by the Greek physician Alexander Trallianus, who flourished in the first half of the sixth century A.D. He directs that this design be engraved on a “Median stone,” which is then to be set in a gold ring and worn by the patient.[286] The fact that the constellation Leo was believed to rule over the stomach, and possibly over the liver also, probably determined the selection of the design. On the reverse of the Ravenna amulet are inscribed the letters K K K, which are believed to stand for Κωλική, “colic.”[287] After noting the power of the jasper (probably the red variety) to check hemorrhages from any part, and its general effect upon the circulation of the blood in reducing the pulse, thus calming desire and quieting the restless mind, Cardano turns to another of the reputed virtues of this stone, that of rendering the wearer victorious in battle. The true reason for this he finds in the stone’s tendency to diminish passion, and hence to render the wearer timid and cautious, for “the timid usually conquer, since they avoid a doubtful contest if possible.” Gesner states that he saw “in the possession of a writer of Lausanne,” a green jasper, bearing the image of a dragon with rays, similar to the gem described by Galen.[288]