The most probable suggestion is that the Algerians and the ancient Irish got it from a common source, namely, the East, and that its introduction into our own islands dates from the time when the traffic in silver bullion from the East commenced. The existence of a trade route which was made use of by the dealers in silver bullion is made clear by the number of finds of Mahomedan silver coins associated with ingots, rings, and ornaments of silver, made both in Scandinavia and in Great Britain. Dr. Hans Hildebrand, in his _Industrial Arts of Scandinavia_ (p. 81), informs us that “considerable stores of such coins, most of them of the Samanid dynasty, have been found in Sweden. It is satisfactorily proved by Russian finds, that these coins were brought from states near the Caspian Sea, through Russia to the shores of the Baltic Sea, and thence to the commerce established by the inhabitants of Gotland over to that island. From Gotland, and probably also by direct intercourse with Russia, the Mahomedan coins were spread over Scandinavia, being of course more common in the eastern provinces of Sweden than in the western and in Norway.” No less than 20,000 Mahomedan silver coins have already been discovered in Sweden, mostly dating between A.D. 880 and 955, the latest belonging to the year A.D. 1010. [Illustration: DETAIL OF ORNAMENT ON THE TARA BROOCH] [Illustration: DETAIL OF ORNAMENT ON THE TARA BROOCH] [Illustration: DETAIL OF ORNAMENT ON THE TARA BROOCH] Penannular brooches have been found in association with Mahomedan coins of the ninth and tenth centuries, at Skaill, in Orkney; at Storr, in Skye; and at Cuerdale, near Preston, in Lancashire. Although the general form of the penannular brooch is probably of Eastern origin, the decorative features vary according to the race of people who adopted it. Thus the examples from Algeria have Mahomedan ornament; those from Gotland, Scandinavian patterns; whilst those from Ireland and Scotland are thoroughly Celtic in design. With the decoration of the foreign specimens we are not now concerned, but a few words with regard to the various types found in Great Britain will form a fitting conclusion to this article. The finest collections of penannular brooches are to be seen in the British Museum, the National Museum of Antiquities of Scotland, in Edinburgh, and in the Museum of the Royal Irish Academy in Dublin. A few good specimens are in private hands, and there is a splendid one from Orton Scar,[420] in Westmoreland, in the Museum of the Society of Antiquaries at Burlington House. [420] _Reliquary_ for 1903, p. 203.