﻿210 ILLUSTRATIONS OF FOSSIL FOOTPRINTS 



were impressed by individuals in all stages of development, from the young to the 

 perfect animal. 



In many localities, as at Wethersfield in Connecticut, the footprints, being impress- 

 ed upon soft and yielding clay, are ruined by subsequent changes ; while at others, as at 

 Turner's Falls, they occur without blemish. So imperfect are the footprints at most 

 localities, that it was not until the year 1843, when my attention was attracted to those 

 at Turner's Falls, that examples occurred sufficiently perfect to exhibit the phalangeal, 

 ungual, and dermoid systems of the toes. Impressions which do not display these essen- 

 tial features are more or less imperfect. In a considerable proportion of the footprints, 

 no doubt, the evidence is so unquestionable, that we cannot hesitate in deciding upon 

 specific characters ; yet to embrace the whole, or even the greater part of them, in any 

 system of classification upon principles of true science, is, in my opinion, impossible. 

 We cannot, with any thing like certainty, restore the anatomical organization of the ani- 

 mals by whom the footprints were impressed ; and until this can be done, any system of 

 nomenclature must be both artificial and arbitrary. The presumption is, that the animals 

 resorted to the ancient shores for subsistence and reproduction. From the impressions 

 of their feet we may infer that they were small or great, that they were or were not ra- 

 pacious, that they were light or heavy, that they were elevated upon long or short legs, 

 and that they were analogous to certain living types ; but beyond this we can hardly go. 

 We cannot determine their individual habits or distinctive organization, which are indis- 

 pensable conditions of specific classification. I therefore neither adopt nor attempt any 

 detailed methodical arrangement ; which can, at best, be little more than an arbitrary in- 

 vention, tending in no degree to advance our knowledge, but rather to involve a most 

 simple subject in inextricable confusion. In a remote era of the earth's history, certain 

 tribes of animals roved upon the soft margins of seas or lakes, and there imprinted their 

 footsteps. The stratum thus impressed was subsequently overspread by a new layer of 

 plastic clay, which was trodden upon in turn, and the impressions preserved by a newer 

 deposit. Page after page of the vast volume of the earth's annals was thus sealed up, to 

 be opened, after the lapse of unnumbered centuries, to our admiring eyes. 



Unfortunately, no osseous remains of the animals themselves have ever been discov- 

 ered. The argillaceous quality of the rock was doubtless unfavorable to their preserva- 

 tion ; yet we might still expect that osseous impressions would occur. Perhaps the 

 thin hollow shell that forms the bones of most birds, permeable by air, would cause the 

 carcass to be floated away in the periodical overflow of the waters, supposing the 

 birds to have perished upon the narrow shores whereon they congregated. It is only 

 upon localities which were periodically submerged that we find footprints ; it must be 



