favourite material with the old Romans for sheathing walls and tables.  Magnificent columns of it were introduced into the temples and triumphal arches.  We find relics of these in the older churches.  Four splendid fluted Corinthian columns of Verde antico, with gilded capitals, support the pediment of the high altar in Sta.  Agnese, in the Piazza Navone, which formerly belonged to the Arch of Marcus Aurelius in the Corso.  A pair of very fine columns of this precious stone flank each of the niches, containing statues of the twelve apostles, in the piers which divide the middle nave from the side ones in the Church of St. John Lateran.  These twenty-four columns are remarkable for the clearness of the white, green, and black colours that occur in them.  They are supposed to have been taken from the Baths of Diocletian.  Two of the splendid composite columns which support the pediment of the altar in the Corsini chapel of this church are of this marble, and were also taken from the Arch of Marcus Aurelius in the Corso.  One most magnificent column of Verde antico has been found, along with seven others of different marbles, in the wall of the narthex of the subterranean Church of San Clemente.  A small portion of it is polished to show the beauty of the material, while the rest is dimmed and incrusted with the grime of age.

Very different from this is the ancient serpentine or ophite of Sparta called the Lapis Lacedaemonius, found in different hills near Krokee, or in Mount Taygetus in Lacedaemon, where the old quarry has recently been opened.  It has a base of dark green with angular crystals of felspar of a lighter green imbedded in it.  It is a truly eruptive rock, occurring in intrusive bosses, or in beds interstratified with gneiss and mica-schist, and owes its various shades of green to the presence of copper.  Owing to its extraordinary hardness, this stone was seldom used for architectural purposes; and the lapidary will charge three times as much for working a fragment of this material into a letter-weight as for making it of any other stone.  A pair of fluted Roman Ionic columns, supporting the pediment of the altar of the chapel of St. John the Baptist, in the Baptistery of St. John Lateran, are the only examples of ophite pillars in Rome.  Next to these the largest masses are a circular tablet, forming part of the splendid sheathing of one of the ambones in the Church of San Lorenzo; and two elliptical tablets, still larger, engrafted upon the pilasters in front of the high altar of St. Paul’s.

The principal use to which this stone was devoted in Rome was the construction of mosaic pavements.  The emperor Alexander Severus introduced into his palaces and public buildings a kind of flooring composed of small squares of green serpentine and red porphyry, wrought into elegant patterns, which became very fashionable, and was called after himself Opus Alexandrinum.  The infamous Heliogabalus had previously paved some