Siluria—Present State of Geology. 319 
vertebrata is good positive evidence on which to argue, still it might 
be contended that such forms may at a future period be found in 
the lower strata. In this work, however, I reason only on: known 
data. Nor is it on this testimony alone, strong, clear, and univer- 
sal as it is, that my view is sustained; for as soon as we pass into 
the formation immediately overlying, and quit the zone wherein the 
first few small fishes are to be detected, we are furnished with colla- 
teral proofs that this was the earliest great step in a progressive 
order of creation. In the following or Devonian period, we are sur- 
rounded by a profusion of larger fossil fishes, with vertebrze for the 
most part very imperfectly ossified, and with dermal skeletons of 
very singular forms, all differing vastly from anything of their class 
in existing nature. These fishes were thus clearly added to the other 
forms of marine life. Again, in this Devonian era we are presented 
_with well-defined land plants, also of much larger dimensions than 
the very rare specimens in the uppermost Silurian, while towards the 
close of the period we meet with an air-breathing reptile. The lit- 
tle telerpeton had groves of tree-ferns or lycopodiaceous plants, and 
even of coniferee, amid the roots of which he could nestle. 
Just as the introduction of cartilaginous fishes (onchus, e.g.) is 
barely traceable at the close of the long Silurian era, so, becoming 
soon afterwards more abundant, they are associated in all younger 
formations with true osseous fishes, whose remains are found inter- 
mixed with the other exuviee of the sea. Putting aside, therefore, 
theory, and judging solely from positive observation, we may fairly 
infer—jirst, That during very long epochs the seas were unoccupied 
by any kind of fishes; secondly, that the earliest discoverable crea- 
tion of this class had an internal framework almost incapable of fos- 
silization, and so left in the strata their teeth and dermal skeletons 
only ; and thirdly, that in the succeeding period the oldest fishes 
having bony vertebree make their scanty appearance, but become 
numerous in the overlying deposits. Are not these absolute data of 
the geologist clear signs of a progress in creation ? 
‘In like manner, there is a progress in the productions of the 
land, the great gurbotiferoue period being marked by the first 
copious and universally abundant terrestrial flora, the prelude to 
which had appeared in the foregoing Devonian epoch. This earliest 
luxuriant ‘tree vegetation, the pabulum of our great coal-fields, is 
also specially remarkable for its spread over many latitudes and lon= 
gitudes, and together with it occur the same common species of 
marine shells, all indicating a more or less equable climate from 
polar to intertropical regions, a phenomenon wholly at variance with 
the present distribution of animal or vegetable life over the surface. 
of the planet. : 
“ Lastly, while the Permian era was distinguished by the dis- 
appearance of the greater number of the primeval types, and by 
