Pacciuchelli says:—“The Anio flows into the Tiber; pure as crystal it meets the tawny stream, and is lost in it, so that there is no more Anio, but the united stream is all Tiber.” So is it with each tributary to the tide of mediæval mythology. The moment it has blended its waters with the great and onward rolling flood, it is impossible to detect it with certainty; it has swollen the stream, but has lost its own identity. If we would analyse a particular myth, we must not go at once to the body of mediæval superstition, but strike at one of the tributaries before its absorption. This we shall proceed to do, and in selecting Norse mythology, we come upon abundant material, pointing naturally to the spot whence it has been derived, as glacial moraines indicate the direction which they have taken, and point to the mountains whence they have fallen. It will not be difficult for us to arrive at the origin of the Northern belief in were-wolves, and the data thus obtained will be useful in assisting us to elucidate much that would otherwise prove obscure in mediæval tradition. Among the old Norse, it was the custom for certain warriors to dress in the skins of the beasts they had slain, and thus to give themselves an air of ferocity, calculated to strike terror into the hearts of their foes. Such dresses are mentioned in some Sagas, without there being any supernatural qualities attached to them. For instance, in the Njála there is mention of a man _i geitheðni_, in goatskin dress. Much in the same way do we hear of Harold Harfagr having in his company a band of berserkir, who were all dressed in wolf-skins, _ulfheðnir_, and this expression, wolf-skin coated, is met with as a man’s name. Thus in the Holmverja Saga, there is mention of a Björn, “son of _Ulfheðin_, wolfskin coat, son of _Ulfhamr_, wolf-shaped, son of _Ulf_, wolf, son of _Ulfhamr_, wolf-shaped, who could change forms.” But the most conclusive passage is in the Vatnsdæla Saga, and is as follows:—“Those berserkir who were called _ulfheðnir_, had got wolf-skins over their mail coats” (c. xvi.) In like manner the word _berserkr_, used of a man possessed of superhuman powers, and subject. to accesses of diabolical fury, was originally applied to one of those doughty champions who went about in bear-sarks, or habits made of bear-skin over their armour. I am well aware that Björn Halldorson’s derivation of berserkr, bare of sark, or destitute of clothing, has been hitherto generally received, but Sveibjörn Egilsson, an indisputable authority, rejects this derivation as untenable, and substitutes for it that which I have adopted.