magnificent in ruin; very different, too, from the _columbaria_, or pigeon-holes, in which the ashes of the less wealthy were packed away; and still more different from the sad undistinguished ditch that received the bodies of the poor:--
"Hoc miserae plebi stabat commune sepulcrum."
[Footnote D: The volcanic rocks are the _Tufa litoide_, very hard, and used for paving and other such purposes; difficult to be quarried, and unfit for graves on account of this difficulty. The _Tufi granulare_, a soft, friable, coarse-grained rock, easily cut,--fitted for excavation. It is in this that the catacombs are made. It is used for very few purposes in Rome. One may now and then see some coarse filling-up of walls done with it, or its square-cut blocks piled up as a fence. The third is the _Pura pozzolana_,--which is the Tufa granulare in a state of compact sand, yielding to the print of the heel, dug like sand, and used extensively in the unsurpassed mortar of the Roman buildings.]
It not unfrequent