At a later period I found myself perplexed in the study of fossil plants by the evident errors of many palæobotanists unacquainted with modern markings on shores, in referring all kinds of mere markings to the vegetable kingdom, and especially to the group of fucoids or seaweeds, which had become a refuge for destitute objects not referable to other kinds of fossils. It thus became necessary to collect and study these objects, as they existed in rocks of different ages, and to compare them with the examples afforded by the modern beach; and perhaps no locality could have afforded better opportunities for this than the immense tidal flats of the finest mud left bare by the great tides of the Bay of Fundy in Nova Scotia. At a more recent period still, the subject has come into great prominence in Europe, and if we are to gauge its importance by the magnitude of the costly illustrated works devoted to it by Delgado, Saporta, Nathorst, and others, and the multitude of scattered papers in scientific periodicals, we should regard it as one of the most salient points in Geology.[149] [149] _Journal of London Geological Society_, vol. vii. p. 239. It may be well further to introduce the subject by a few extracts from Lyell's work above referred to. "The sediment with which the waters are charged is extremely fine, being derived from the destruction of cliffs of red sandstone and shale, belonging chiefly to the coal measures. On the borders of even the smallest estuaries communicating with a bay, in which the tides rise sixty feet and upwards, large areas are laid dry for nearly a fortnight between the spring and neap tides, and the mud is then baked in summer by a hot sun, so that it becomes solidified and traversed by cracks caused by shrinkage. Portions of the hardened mud may then be taken up and removed without injury. On examining the edges of each slab we observe numerous layers, formed by successive tides, usually very thin, sometimes only one-tenth of an inch thick, of unequal thickness, however, because, according to Dr. Webster, the night tides rising a foot higher than the day tides throw down more sediment. When a shower of rain falls, the highest portion of the mud-covered flat is usually too hard to receive any impressions; while that recently uncovered by the tide, near the water's edge, is too soft. Between these areas a zone occurs almost as smooth and even as a looking-glass, on which every drop forms a cavity of circular or oval form; and if the shower be transient, these pits retain their shape permanently, being dried by the sun, and being then too firm to be effaced by the action of the succeeding tide, which deposits upon them a new layer of mud. Hence we find, on splitting open a slab an inch or more thick, on the upper surface of which the marks of recent rain occur, that an inferior layer, deposited perhaps ten or fourteen tides previously, exhibits on its under surface perfect casts of rain prints which stand out in