In the Triassic, or New Red argillaceous sandstones of the valley of the Connecticut River, in North America, some very remarkable phenomena have, however, been discovered, and which in the opinions of many eminent observers render it highly probable, that at the period when these strata were deposited, numerous birds, some of colossal magnitude, abounded on the then dry land. When slabs of these sandstones are split asunder, or exposed, so as to exhibit the sedimentary surface which separates one layer from another, the foot-prints of many species of bipeds are perceived deeply impressed on the stone, and disposed in such manner as to prove that they are the tracks of animals that walked over the surface of the deposit when it was in a soft or plastic state. The close analogy of these imprints to those of birds' feet, not only in their general resemblance, but also in the disposition of the tracks, and in the relation of the distance of the stride, and the depth and shallowness of the impressions, to the size of the respective feet, tends to corroborate the inference first enunciated by Professor Hitchcock, and subsequently confirmed by other geologists, that these mysterious markings on the rock, are natural records of the existence of various tribes of birds during the Triassic period;[87] but unfortunately the only certain evidence of the correctness of this opinion--remains of the skeletons--is wanting; not a vestige of a vertebrated animal of a higher class than fishes and reptiles has been discovered.[88] [Footnote 87: Travels in North America, vol. ii. pl. 7.] [Footnote 88: See Wonders of Geology, vol. ii. p. 556. Ornithichnites, or Fossil Footprints of Birds; Medals of Creation, vol. i. p. 808.] In the vast fluviatile formation--the Wealden--of the south-east of England, which abounds in the remains of terrestrial plants and reptiles, many fragments of bones of such tenuity as to indicate that they belonged to animals capable of flight, have from time to time been collected since my first discovery and announcement, in 1822, of supposed birds' bones in the strata of Tilgate Forest. Some of these relics were declared by Baron Cuvier, and subsequently by Professor Owen, to be unquestionably those of birds; probably some species of waders. But recent observations have rendered it doubtful whether all the specimens of this class from the Wealden, like those from Stonesfield, are not to be regarded as referable to flying reptiles (Pterodactyles).[89] [Footnote 89: Wonders of Geology, vol. i. p. 438, 440. I still think it probable, however, that bones of birds will be detected among the Wealden fossils.]