1 
PALAEOZOIC CLASSIFICATION OF THE BRITISH ISLES. 
strata from those which went before them, and were deposited ere life had been 
breathed into the waters? If such questions could be satisfactorily answered, 
then, indeed, would geology not merely have developed a wondrous succession of 
the ancient works of Nature, but young as she is among the sciences, would have 
been the first to afford undeniable proofs of a beginning. Such, at all events, are 
among the problems which we have been endeavouring to solve during the last 
fourteen years, by examining the earlier productions of the earth, and by researches 
in the field carried on through various parts of Europe and along the borders 
of Asia. 
Geologists have generally admitted, that those labours in the British Isles, which 
terminated with the establishment of the Silurian system, made the first unequi- 
vocal step in this inquiry, by affording clear evidences of a natural descending 
order, from the Carboniferous formations, that had previously been well illus- 
trated 1 2 , down to a group of deposits essentially differing from all above them in 
the various forms of animal life which they contained. To these peculiar lower 
deposits, whose members were then first classified and their fossil remains de- 
scribed, one of the authors of this work applied a term derived from a region for- 
merly occupied by the British Silurian people, and affording clear evidences of a 
certain order and succession in primaeval life. In addition to the establishment of 
a normal distinction between the Carboniferous and Silurian strata, it was then 
also shown, that certain accumulations of great thickness, separating these two 
groups, and long known under the name of the Old Red Sandstone, were charac- 
terized, as in Scotland, by ichthyolites, which in the Silurian region were perfectly 
distinct in form from any remains of that class in the carboniferous beds above or 
in the Silurian strata below. At the period when these chief results were pub- 
lished, the Old Red Sandstone had afforded no remains whatever of mollusca ; yet 
judging from the enormous thickness of this system of rocks, as well as from the 
diversity of character of the fossils found in the overlying and underlying forma- 
tions, we suggested, that should future researches bring to light molluscous remains 
in the Old Red Sandstone, they would, like the ichthyolites, be found to be peculiar 
to the intermediary rocks in which they w T ere entombed*. This surmise has been 
1 See the work of Professor Phillips, ‘ Geology of Yorkshire,’ vol. ii., which contains the earliest good 
monograph of the organic contents of the Carboniferous system of England. 
2 See Silurian System, p. 585. Although that work bears the date of 1839, we may observe that it 
was really completed in 1838. The term Silurian and the classification implied thereby were indeed pro- 
