6 PALZEONTOLOGY OF NEW-YORK. 
condition of the earth unfavorable to animal development, and we perceive the gradual 
change, which, in the next period, presents us with swarms of animated existences. If we 
can, in imagination, allow ourselves to go back to the preceding epoch—to fancy the earth 
enveloped in one waste of ocean, save perhaps a few rocky peaks; when the natural 
agitation of the waters by the winds was increased by volcanic or igneous outburstings ; 
while the rocky points were abraded, and thence fine sand and pebbles spread over the 
bed of the ocean, we behold life, struggling into existence in this stormy period, only 
manifested in the fragile yet enduring form of the little Lingula, while an apparently 
rootless leafless plant is the representative of the vegetable kingdom. 
Look forward from this period to a gradual change—a more congenial element to the 
inhabitants of the ocean comes, in the form of calcareous matter, and new organisms are 
gradually called into existence. Still the heated waters bear their burden of silex in solution, 
and now they permeate every portion of this habitation of the newborn vitality, destroying 
the living, enveloping the dead in a siliceous paste, and preventing that development of 
numbers which awaits only a more congenial cendition. 
Such, indeed, we have every reason to believe, was the state of things at this period. 
Numerous hot springs, bursting out from fissures or faults of the lower strata, penetrated 
with their heated waters the lower beds of this rock during their deposition, and while in 
a condition to be so affected. The superincumbent waters doubtless partook in some degree 
of this condition, and became a less congenial abode for the testaceous tribes just called 
into being. Still this condition does not seem to have been unfitted to the development of 
the singular vegetable forms which appear in great numbers, and which constitute a large 
portion of some thin layers (the fucoidal layers) near the base of the formation. 
The first metagenic interval lies between the deposition of the rock previously noticed, 
and the termination of this one, and may be regarded as the interval in which certain 
conditions were assumed by the elements, favorable to those forms of life, which continued 
through a long period, even indeed to the close of the paleozoic epoch. 
