THE OLD RED SANDSTONE. 227 
remains first occur, over what we may term the densely 
crowded platform of violent death, the explorer may labor 
for hours together without finding a single scale. 
It is worthy of remark, however, that this upper bed 
abounds quite as much in the peculiar vegetable impressions 
of the formation as the lower platform itself. An abundance 
equally great occurs in some localities only a few inches over 
the line of the exterminating catastrophe. Thickets of ex- 
actly the same alge, amid which the fish of the formation 
had sheltered when living, grew luxuriantly over their graves 
when dead. The agencies of destruction which annihilated 
the animal life of so extended an area, spared its vegetation ; 
just as the identical forests that had waved over the semi- 
civilized aborigines of North America continued to wave over 
the more savage red men, their successors, long after the 
original race had been exterminated. ‘The inference deduci- 
ble from the fact, though sufficiently simple, seems in a geo- 
logical point of view a not unimportant one. The flora of a 
system may long survive its fauna; so that that may be but 
one formation, regarded with reference to plants, which may 
be two or more formations, regarded with reference to ani- 
mals. No instance of any such phenomenon occurs in the 
later geological periods. The changes in animal and vege- 
table life appear to have run parallel to each other from the 
times of the tertiary formations down to those of the coal; 
but in the earlier deposits the case must have been different. 
The animal organisms of the newer Silurian strata form es- 
sentially different groups from those of the Lower Old Red 
Sandstone, and both differ from those of the Cornstone divis- 
ions; and yet the greater portion of their vegetable remains 
seem the same. ‘The stem-like impressions of the fucoid bed 
of the Upper Ludlow Rocks cannot be distinguished from 
