At one point where the rock was almost entirely solid and without flaw or crevice, and where it was clear that the passages were entirely the work of the ants, we measured a tunnel by worming a straw down it, and found it to be ten inches in length. We subsequently traced this tunnel or rock gallery down until it communicated with a chamber filled with winged ants and seeds of several kinds. This granary was horizontal, and merely an enlargement of an ordinary gallery of a compressed spindle-shape, flattened from above downwards, measuring as nearly as I could estimate three inches in length, by a trifle less than an inch in breadth, and half an inch in height. The walls were tolerably smooth, but not prepared or glazed in the way that certain small terminal cells which I shall shortly describe were. The surfaces, however, had a very different appearance to that of the surrounding sandstone, being of a darker and brownish colour, and seeming to be coated with some kind of dressing or cement. One of these tunnels at first took a horizontal course for two and a half inches, then descended vertically for an inch and a half to a point where it made two horizontal branches, and from these latter several other vertical galleries descended, two of which we were able to trace until they expanded into a cluster of small pear-shaped cells, the walls of which were quite smooth and very carefully laid with plates of mica and cement. I was able to draw this on the spot, Fig. A, Plate V., while Mr. Lightbody worked it out piecemeal with hammer and chisel. It was unfortunately impossible to secure more than very imperfect fragments as specimens. These terminal cells were empty when we came to them, but it is quite possible that the ants may have conveyed away larvæ or winged ants from them, having received abundant notice of the coming danger from the continued jarring of the chisel-work. One entrance to this nest lay in a small accumulation of soil in a hollow of the rock, and it was at this point that the refuse from the nest was cast out. Indeed, had it not been for the accidental circumstance of my having traced the ants to the newly hewn step in the sandstone, I might never have discovered the fact that the nests are sometimes carried deep into the living rock. [Illustration: _Plate VI._]