They were beautiful and tiny, some sort of geological anomaly.
Others are relics of an earlier geological period, when land areas 1 Authorities differ in their methods and results of computation of these and other similar measurements.
The observation of the facts of the geological succession of the forms of life.
I have said that Walden has no visible inlet nor outlet, but it is on the one hand distantly and indirectly related to Flint's Pond, which is more elevated, by a chain of small ponds coming from that quarter, and on the other directly and manifestly to Concord River, which is lower, by a similar chain of ponds through which in some other geological period it may have flowed, and by a little digging, which God forbid, it can be made to flow thither again.
The " mudfish " of Queensland (Ceratodus Forsteri) belongs to an ancient order of fishes - the Dipnoi, only a few species of which have survived from past geological periods.