into the mine in which he was working, had crushed his leg and given him a limp for life; and if he had been a few inches nearer to it would have broken his back. The manner in which such trees become fossilized may be explained as follows:--Imagine a forest of Sigillariæ growing on a low flat. This becomes submerged by subsidence or inundation, the soil is buried under several feet of sand or mud, and the trees killed by this agency stand up as bare and lifeless trunks. The waters subside, and the trees rapidly decay, the larvæ of wood-boring insects perhaps aiding in the process, as they now do in the American woods. The dense coaly outer bark alone resists decomposition, and stands as a hollow cylinder until prostrated by the wind or by the waters of another inundation, while perhaps a second forest or jungle has sprung up on the new surface. When it falls, the part buried in the soil becomes an open hole, with a heap of shreds of wood and bark in the bottom. Such a place becomes a fit retreat for gally-worms and land-snails; and reptiles pursuing such animals, or pursued by their own enemies, or heedlessly scrambling among the fallen trunks, may easily fall into such holes and remain as prisoners. I remember to have observed, when a boy, a row of post-holes dug across a pasture-field and left open for a few days, and that in almost every hole one or two toads were prisoners. This was the fate which must have often befallen the smaller reptiles of the coal forests in the natural post-holes left by the decay of the Sigillariæ. Yet it may be readily understood that the combination of circumstances which would effect this result must have been rare, and consequently this curious fact has been as yet observed only in the coal formation of Nova Scotia; and in it only in one locality, and in this in one only out of more then sixty beds in which erect trees have been found. But these hollow trees must be filled up in order to preserve their contents; and as inundation and subsequent decay have been the grave-diggers for the reptiles, so inundations filled up their graves with sand, to be subsequently hardened into sandstone, burying up at the same time the newer vegetation which had grown upon the former surface. The idea that something interesting might be found in these erect stumps, first occurred to Sir C. Lyell and the writer while exploring the beautiful coast cliffs of Western Nova Scotia in 1851; and it was in examining the fragments scattered on the beach that we found the bones of the first Carboniferous reptile discovered in America, and the shell of the oldest known land snail.