mice ejected from
submarine volcanoes whose craters have been completely obliterated. It
reposes upon marine tertiary deposits, and over it, near the Church of
Sta. Agnese, where it is still quarried for building stone, rests a
quaternary deposit, in which numerous remains of primeval elephants
have been found. Though the Consular or Republican period was a very
stormy one, and the reconstruction of the city, after its partial
demolition by the Gauls, seems to have been too hurried to allow much
attention to be paid to the materials and designs of architecture, yet
there are numerous indications in the existing remains of that period
that there was a decided advance in these respects upon the ruder art
of a former age. Finer and more ornamental varieties of volcanic stone
were introduced from a distance, such as the _peperino_ or
grayish-green tufa of the Alban Hills, the _Lapis Albanus_ of the
ancients, with its glittering particles of mica interspersed
throughout its mass; the hard basaltine lava from a quarry near the
tomb of Caecilia Metella, on the Appian Way, and from the bed of the
Lago della Colonna, once the celebrated Lake Regillus, to which the
name of _Lapis Tusculanus_ or _Selce_ was given; and the _Lapis
Gabinus_ or _Sperone_, a compact volcanic concrete found in the
neighbourhood of the ancient Gabii on the road to Tivoli, extensively
used in the construction of the earliest monuments, particularly the
Tabularium and the huge Arco de Pantani. Brick was also largely
employed in the construction of the foundations and inner walls of
public buildings, being arranged at a later date into ornamental
patterns, to which the names of _opus incertum_ and _opus reticulatum_
were given; and in the manufacture of this substance, which they were
probably at first taught by the Etruscan artificers of Veii in the
neighbourhood, the Romans reached a high degree of perfection. The
earliest tombs along the Appian Way were constructed of these
different varieties of building materials. The sarcophagi of the
Scipios were hollowed out of simple blocks of peperino stone; and the
sculptor's art and the material in which he wrought were worthy of the
severe simplicity of the heroic age.

But towards the close of the Republican period, Rome began to be
distinguished for the magnificence of its public monuments. As its
area of conquest spread, so did its luxury increase. New divinities
were introduced from foreign countries, and