CHAP. IV. OF ANCIENT BUILDINGS. 191 



open burrows on the broken summit of the 

 eastern wall (W in Fig. 8) ; and, on Septem- 

 ber 15th, other burrows similarly situated 

 were seen. -It should also be noted that in 

 the perpendicular side of the trench (which 

 was much deeper than is represented in 

 Fig. 8) three recent burrows were seen, which 

 ran obliquely far down beneath the base of 

 the old wall. 



We thus see that many worms lived beneath 

 the floor and the walls of the atrium at the 

 time when the excavations were made ; and 

 that they afterwards almost daily brought up 

 earth to the surface from a considerable 

 depth. There is not the slightest reason to 

 doubt that worms have acted in this manner 

 ever since the period when the concrete was 

 sufficiently decayed to allow them to penetrate 

 it; and even before that period they would 

 have lived beneath the floor, as soon as it 

 became pervious to rain, so that the soil 

 beneath was kept damp. The floor and the 

 walls must therefore have been continually 

 undermined ; and fine earth must have been 

 heaped on them during many centuries, 

 perhaps for a thousand years. If the burrows 



