These European rocks have
not yet produced a single land-shell, in spite of the millions of tons of coal
annually extracted, and the many hundreds of soils replete with the fossil roots
of trees, and the erect trunks and stumps preserved in the position in which
they grew. In many large coal-fields we continue as much in the dark respecting
the invertebrate air-breathers then living, as if the coal had been thrown down
in mid-ocean. The early date of the carboniferous strata can not explain the
enigma, because we know that while the land supported a luxuriant vegetation,
the contemporaneous seas swarmed with life-- with Articulata, Mollusca, Radiata,
and Fishes. The perplexity in which we are involved when we attempt to solve
this problem may be owing partly to our want of diligence as collectors, but
still more perhaps to ignorance of the laws which govern the fossilisation of
land-animals, whether of high or low degree.
CARBONIFEROUS RAIN-PRINTS.
(FIGURES 444 and 445. On green shale, from Cape Breton, Nova Scotia.
(FIGURE 444. Carboniferous rain-prints with worm-tracks (a, b) on green shale,
from Cape Breton, Nova Scotia.
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