The lofty walls of tufa round the edge of the substructure were for the lifts, _not_ for the canals _ib._ XV. Other lifts for men and dogs on each side of the central passage _ib._ An arch of tufa shaken by an earthquake, supported by a brick wall of the time of Nero, and another half-arch of the same period abutting against it _ib._ IX., XV. Two small square chambers of Nero are enclosed in the travertine walls of the Flavian Emperors 15 Augustus intended to build an amphitheatre here, but did not _ib._ The tufa walls are probably the work of Scaurus, in the time of Sylla _ib._ V. In these walls are vertical grooves for the lifts and cages _ib._ Animals were brought from the _vivaria_ outside the walls in cages, called _pegmata_ _ib._ VI. Podium protected by wire netting and bars 16 Seneca describes the _pegmata_ in this theatre _ib._ XVI. One _vivarium_ was at the Prætorian Camp, the other at the Sessorium _ib._ A small stream of water ran in front of the dens 17 A pit 4 ft. square, for a man to descend to feed the animals, behind each door _ib._ The tufa walls were in some parts supported by brick walls of the Flavian Emperors _ib._ IX. Curious wooden framework on the floor of the central passage, believed to have been a cradle, or dry-dock 18 VII. The general plan of the Colosseum is oval, with galleries, _vomitoria_, &c. _ib._ VIII. A large part destroyed by having been used as a stone quarry _ib._ The north side the only part at all perfect _ib._ I. A great deal of tufa used to fill up between the piers of travertine _ib._ XXI. The tufa taken from the second wall of Rome close at hand _ib._ Travertine piers cut through the older wall to carry the upper gallery 19 XX. The front is of three periods, the upper storey added a century after the rest _ib._ A great mixture of stone and brick in the construction _ib._ Name of the architect not known; Gaudentius only employed upon it 20 Views on coins, and in sculpture on the tomb of the Aterii, of the first century _ib._ Machine for raising stones for the walls 21