A peculiar fossil was known to the Germans by the name of Mutterstein, and is called _hysterolithus_ in the Latin treatises of Agricola, De Boot, etc., a word of Greek derivation signifying the resemblance of the object to an organ of the body. These fossils are formed from the contents of certain shells, and retain the shape of the enclosing shell, which has broken away. Some of these formations were called _enorchi_ from a fancied resemblance to another organ and were regarded as phallic emblems, while others were thought to figure the heart, especially large specimens being named _bucardites_, or “ox-hearts.” This name is already employed by Pliny. The _hysterolithus_ was used to cure various female diseases, and to the _bucardites_ was accorded among other virtues that of increasing the wearer’s courage.[402] The _hysterolithus_ is believed to be the same as the _autoglyphus_ mentioned by pseudo-Plutarch as having been found in the river Sagaris, in Asia Minor. Its peculiar shape was regarded as symbolizing Cybele, the mother of the gods, and the story ran that if one of the unfortunate male victims of Eastern jealousy should obtain a stone of this kind he would become reconciled to his sad lot and would cease to regret his lost manhood. [Illustration: Types of Ombria (Fossil Sea Urchins). From Mercati’s “Metallotheca Vaticana,” Romæ, 1719. ] If we were inclined to accord the title of precious stones to stones greatly esteemed for their talismanic virtues, a high place in this category would be assigned to the sâlagrâma-stone of the Hindus.[403] Among the aboriginal inhabitants of India this was regarded as a symbol of the female principle in nature, and of its representative the goddess Prakrti, and in the later Hindu belief the stone was looked upon as the special emblem of the god Vishnu, the “Preserver,” the second personage of the Hindu Trimurti. It is therefore ardently revered by those who are more especially devoted to the worship of Vishnu. These stones are fossil formations, either of ammonites or univalve mollusks of a spiral order, and consist of a number of spirals surrounding a circular, central perforation. They are generally the hardened filling of the shell itself, which has entirely weathered away. For the stone to be an effectual talisman, the diameter of the perforation should not exceed one-eighth of the total diameter of the sâlagrâma. The best specimens are said to be found in Nepal, on the upper course of the Gandakî, which flows into the Ganges from the north, and is called the Salagrama River, because the sacred stone is found in it. [Illustration: Cornu ammonis (Fossil Nautilus.) From “Museum Wormianum,” Lugduni Batavorum, 1655. ]