The enormous size of some of the foot-marks is calculated to excite great surprise. I have in my possession (through the kindness of Dr. Deane) imprints that prove the size of the foot to have been fifteen inches in length, and ten inches in width, exclusive of the hind claw, which is present in some species, and is here two inches long. The foot-prints of this biped when in a consecutive series of five or six, are from four to six feet apart; which, of course, must have been the length of the stride; the longest stride was probably made by the animal when running; the shortest, when walking at a moderate pace. These footsteps indicate proportions so far exceeding those of all known living bipeds,—for the foot of the African ostrich is but ten inches long,—that the geologist may be pardoned for having hesitated to adopt the opinions of the American savans, in the absence of any relics of the osseous structure of the supposed birds; although sanctioned by the high authority of Dr. Buckland, who, from the first, concurred in the views of Professor Hitchcock (Bd. ii. p. 39): but this objection has been in a great measure removed by the discovery of the remains of the gigantic Moa or Dinornis of New Zealand, with feet equal in magnitude to the largest of the Connecticut foot-prints. See p. 763, and Pict. Atlas, frontispiece. Professor Hitchcock is of opinion that upwards of forty species of these biped foot-prints may be distinguished. Foot-prints referable to chelonians, batrachians, and lizards are associated with the above.[727]
[727] Trans. Amer. Phil. Soc. n. s. vol. x. pt. ii. p. 312.
In the New Red Sandstone of Stourton Hill, near Liverpool, Mr. Cunningham has observed tridactylous, webbed foot-prints,[728] 21/2 inches long, which he refers to a bird; Mr. Hawkshaw also noticed some bird-like tracks at Lymm; and Professor Harkness met with a trace of a biped at Weston Point, near Runcorn. These appear to be the only indications of ornithoidichnites in the Trias of England; and these are very obscure.
[728] These are accompanied by cheirotherian prints, and by the cast of an impression quite similar to that made on the sands of the sea-beach of to day, by the Medusa (sea-nettle or jelly-fish) left by the reflux of the tide and exposed to a few hours of sunshine. Mr. Cunningham and Mr. Pidgeon have furnished a figure of this interesting impression of the "jelly-fish," which has left "the solid memorial of its evanescent existence en the ancient strand" of the Triassic sea, showing that the physical conditions of land, water, and atmosphere were the same then as those that now obtain.—Liverpool Lit. Phil. Soc. Proc. 1848, p. 128, fig. 1. A similar imprint on a Jurassic rock in Germany is referred to at p. 280.
In the Wealden of Hastings and the Isle of Wight, the natural casts of large tridactylous foot-prints have been observed by Mr. Taggart and Mr. Beckles (see Quart. Journ. Geol. Soc. vol. ii. p. 267, vol. vii. p. 117, vol. viii. p. 396, and Geol. Isle of Wight, p. 328), but as yet no solution of the mystery at present enwrapping these gigantic, tridactylous, biped (?) ichnolites has presented itself: we only know that the creature that left them traversed the borders of the mighty river which floated down the bulky carcases of the Hylæosaur and Iguanodon.
ON COLLECTING FOSSIL BIRDS.
On Collecting the Fossil Remains of Birds.—Notwithstanding the extreme rarity of fossils of this class, the student should not be discouraged in his search for the remains of Birds in the secondary rocks. That far more instructive specimens than any that have fallen under my observation may be discovered in the Wealden strata by diligent research, there can be no reasonable doubt. It is also very probable that the Stonesfield slate, which abounds in remains of terrestrial plants and animals, will be found to contain Ornitholites. It is important for the collector to bear in mind, that when only a fragment of the shaft of a bone remains imbedded in the stone, if the imprint of the other portions be preserved, he may obtain a knowledge of the form of the extremities; in the same manner as the external markings of the surface of a shell may be ascertained, when the shell itself is lost or destroyed, and a smooth stony cast of the internal cavity only is left. The same remark will apply to the bones of reptiles and other animals; for example, a perfect leg-bone may be imbedded in a block of limestone; but, when exposed by breaking the stone, a portion of the shaft may alone remain attached, and both extremities be shattered to pieces by the concussion of the blow; yet, if the impression remains, the entire form of the original may be determined.
The foot-prints, not only of birds, but of reptiles and other animals, should be diligently sought for on the surfaces of laminated strata of sand and clay, and especially where the presence of ripple-marks, and the impressions of rain-drops, indicate that the beds were deposited in shallow water. The forest-marble flags at Castle Comb, north of Bath, the Stonesfield slates, and the sandstones around Horsham (in Sussex), and particularly at Stammerham (see Geol. S. E. p. 213), are often rippled, and it is therefore probable that the foot-prints of some of the Oolitic and Wealden quadrupeds and bipeds, if such existed, will sooner or later be discovered.