6 TAUEONTOLOGT OF NEW-YORK. 



condition of ilic 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 tlie 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 condition. 



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 

 ihrough a long period^ even indeed to the close of the palseozoic epoch. 



