OniitJiichnoIogy. 337 



in these simple foot marks, the existence, and some of the habits, of 

 an interesting class of animals is proved, at a period so remote, that 

 the entire population of the globe has since been changed, at least 

 once or twice, and probably several times more. For, to say noth- 

 ing of minor divisions of the strata, the animals and plants of the 

 secondary rocks must have all been extinct, before the creation of 

 those in the tertiary deposits, and most of these last must have ceased 

 to exist before the production of the present races. The number of 

 years that have since elapsed, we cannot even conjecture ; for, in 

 respect to all the races of animals and plants that have occupied 

 the globe, previous to the existing tribes, the scriptures are silent, 

 giving us to understand merely, that a period of indefinite duration 

 intervened, between "the beginning" and the creation of man ; and 

 geological monuments, although they clearly point out successive 

 epochs in the natural history of the globe, yet furnish us with few 

 chronological dates. 



It may prove, also, an instructive lesson to the geologist, that the 

 mere foot marks of these early animals should have remained so 

 distinct, although every relic of their skeletons has disappeared.* If 

 birds lived during the deposition of new red sandstone, they doubt- 

 less existed during the formation of each successive group of rocks 

 to the highest. Yet, with perhaps one or two very doubtful exam- 

 ples, no trace of them is found in all the wide interval between the 

 red sandstone and the tertiary beds around Paris. f Surely, the geolo- 

 gist will be led to enquire, whether he has not been too hasty in in- 

 ferring the non-existence of the more perfect animals and plants, in 

 the earlier times of our globe ; and whether, after all, it may not be 

 that they did exist, even along with the earliest animals and plants, 

 which we now find imbedded in the strata. The recent discovery of 

 phenogamian vegetables in Scotland, below the coal formation, gives 

 additional force to this suggestion.! 



In pursuing my investigations on this subject, I confess that I was 

 greatly surprised to discover so readily, so many distinct species of 

 the Ornithichnites, or rather distinct genera of birds, for such I can 

 hardly doubt they are. All the present Grallae in Massachusetts do 



* Their bones may yet be found. — Ed. 



i Dr. Mantell has recently described them in the Wealden, below the chalk — 

 above the oolite. See our micellanies. — Ed. 

 t Observations on Fossil Vegetables; by Henry Witham, Esq. Edinburgh, 1831. 

 Vol. XXIX.— No. 2. 43 



