The Romans excelled in the art of designing and executing mosaic pavements, abundant remains of which have been preserved. These were of various kinds. There was the _pavimentum sectile_, composed of pieces of marble of various sizes, shapes, and colours arranged in uniform sets, so as to form when put together an ornamental pattern; the _pavimentum tessellatum_, in which the pieces of marble, though variously coloured, were all of the same size and shape, generally small squares; the _pavimentum vermiculatum,_ composed of very small pieces of coloured marble of irregular shape so arranged as to portray objects in their natural shapes and colours; and finally the _pavimentum scalpturatum_, in which the design was engraved or inlaid. _Opus alexandrinum_ is a variant of _sectile_. [Illustration: FIG. 33.--Mosaic at Salzburg. (Kreuzer.)] Several Roman pavements embodying labyrinthine devices, and in some cases commemorating the victory of Theseus over the Minotaur, or other exploits of the hero, have come to light from time to time, not only on the continent of Europe but also in England; they are usually executed in _opus alexandrinum_. Fig. 33 shows in outline a beautiful specimen, 18 ft. long and 15 ft. broad, discovered at Salzburg, in Austria. It bears the device of a labyrinth, with, at the centre, a representation of Theseus about to give the fatal blow to the Minotaur. On the left side we see Theseus and Ariadne joining hands over the altar. In the upper panel Theseus appears to be putting Ariadne ashore, and to the right we see the disconsolate maiden deserted by her lover, presumably on the Isle of Naxos. A labyrinth of the type shown also occurs on a Roman mosaic which was unearthed in the churchyard at Caerleon-on-Usk. It was in a poor state of preservation, but sufficient remains to show that the labyrinth, of a design similar to that of the Salzburg specimen, is surrounded by scrolls proceeding from two vases (Fig. 34). A very fine specimen of this type of labyrinth was discovered in 1904 beneath a ploughed field at Harpham, in the East Riding of Yorkshire. Another, of which details are not to hand, is said to have been found in Northamptonshire. In 1790 a pavement, about eighteen feet by twelve, was unearthed at Aix, near Marseilles. It portrayed the combat between Theseus and the Minotaur, within a framed square, the remainder of the mosaic consisting of a complicated interlaced meander representing the labyrinth. In Fig. 35 is reproduced from A. de Caumont's "Abécédaire d'Archéologie" a rough sketch of the Roman baths at Verdes (Loir-et-Cher), showing a pavement with a labyrinth mosaic. A pavement found in 1830 at Cormerod, in the Canton of Friburg, Switzerland, is shown in Fig. 36. A few years afterwards another was brought to light in the neighbouring Canton of Vaud, from beneath the ruins of the ancient town of Orbe.