were crowned with fronds of marvelous dimensions; the stems of the sigillarias shed their leaves rapidly; and the remains of all these rank growths were incessantly accumulating in a sultry shade on a water soaked soil. We can conceive the enormous production of humus. Decomposition was accelerated by every rain, and the whole mass was reduced, down to the very bottom, to a black pulp; and this is why, notwithstanding we have such abundant materials, we meet so many difficulties in reconstructing the types. The fallen trunks seldom remained whole, but swelled and burst. The soft and porous parts gave way first, then the dense and fibrous parts were detached from the cortical mass; that, more tenacious and firm, spread out and resisted longer than the rest. Nothing remained of the fern-stems but the peripheric sheath or the disaggregated interior fibers; of the cordaites, sigillarias, and lepidodendrons only the cortical regions. The detached leaves formed other accumulations; and all these heaps, standing as obstructions in different places, were waiting for the arrival and passage of the water to yield to it innumerable fragments in very unequal degrees of decomposition. When the great rains came on, the waters, filtering in from every side, trickling down all the slopes, gathered here and there in temporary lakes, and finally overcame all the dams of organic matter they met—an immense mass of détritus going down to the lacustrine center. With these old and disorganized residues, the rains, which we must imagine to have been torrential, brought down also everything that would yield to their impulsion—tree-trunks, leaves, young shoots, and at times entire plants. It is these remains, so fresh in condition, these leaves so delicate, and clearly defined, these organs so whole which we see in our collections distinguishable in their slightest details, and lying spread out in the leaves of the great herbarium of which it is our privilege to turn the pages.
M. Grand' Eury's theory does not appear to offer anything that is discordant either with ancient phenomena or with those of more recent periods. It possibly has its place marked even now among the grand scenes of contemporary nature. We read in the narratives of the travelers who have ascended the great rivers of the interior of Africa, the Nile, for example, how their boats have been stopped for days at a time by submerged remains and the accumulations of plants hiding the river on which they were floating. In the face of such pictures, which show us sedges, water-lilies, and immense colonies of floating plants, under which the river has disappeared, while its eddies, its lagoons, and its deep basins are temporarily flooded after having been dry for months, we can not escape being carried back in mind to the phenomena, doubtlessly not quite parallel, but assuredly of the same order, to which was due the formation of the coals and lignites in ancient epochs. These were certainly not accidental or episodical phenomena, produced by circumstances which, once realized, were never to appear again, but occurred in the course of a series of analogous combinations of condi-
