Mosaic obviously originated in pavement, and the introduc- tion of ornamental pavement was probably suggested by Oriental tapestry. A pavement, pavimentum , is strictly a flooring [SuttcSof, whence Sams, and ram]^ a carpet or rug, — laid on the floor or stratum, composed of flags, slabs, or pebbles, bricks, tiles, or shells, set in a cement, and beaten down [pavio] with a rammer or pavicula ; and the classical writers [Pliny, Bk. xxxvi] distin- guish pavements by different names, according to their situation, structure, and decoration.

The paved floors of rooms and passages were designated pavimmta subtegulanea , and pavements in the open air, particu- larly those laid on the flat roofs of houses, pavimenta subdialia. The pavimentum sect He was composed of different-colored marbles cut [secta] into regular forms, such as favus^ like the cells [hexagons] of a honeycomb ; trigonum, triangular; scutula , rhomb-shaped ; and tessera, with its diminutive fes sella , a cube.

All these forms might be not only of cut marble or other stone, but of glass or other composition. The abaculus [c^Wo-kos] was a small tile or die [tessera] of glass, or o tlier compo- sition, stained of various colors in imitation of precious stones.

The pavimentum iessellaiunt , or tesseris struct urn, was a sectile pavement, composed of large tessera*

The pavimentum vermiculatum was composed of smaller tessera , arranged, not in diapers and geometrical figures, but so as to represent natural objects, as in pictures, by lines of em- bedded tessera, which necessarily turned and twisted about like the tracks of worms. This vermicular mosaic was divided into opus majus, composed of larger tessera , opus medium , of smaller, and opus minus vermiculatum , composed of very minute and delicate tessdim , almost spicules .

In the pavimentum scalpturatum the marble was cut out in the shape of the figures intended to be represented in the mosaic,