observations already offered on the ripple-marks on sandstone (see p. 382) render it unnecessary to explain the preservation of imprints of this nature. Similar appearances

have since been observed on the Triassic sandstone near Stourton and Runcorn in Cheshire, and in several places in Germany, but no bones of tortoises have been discovered in these strata.

A discovery of a like nature was made soon afterwards in the New Red sandstone near Hildburghausen, in Saxony. Numerous imprints of the feet of some large quadrupeds, having the fore-paws much smaller than the hinder, were observed on the exposed surfaces of some slabs of rippled sandstone: and similar footsteps have been found in the quarries at Stourton, Taporley, and Lymm in Cheshire, at Annan in South Scotland, and near Warwick. These imprints are on the face of each successive layer of stone; and on some of the slabs not only are there foot-prints of various kinds of animals that walked over the stone when it was in the state of soft sand, but also the impressions of rain-drops. Some of the recently exposed surfaces present a blistered or warty appearance, being covered either with little hemispherical eminences, or with depressions; and these, upon an accurate investigation of the phenomena, prcve to have been the effect of rain, which fell while the surface was soft and impressible. On many of the slabs the forms of the rain-drops and of the foot-prints appear in relief, being casts of the surface upon which the impressions were made; while on the clay corresponding hollows are apparent (as in Lign. 133).

Chirotherium.-The foot-prints found on the sandstones and shales above referred to are of various kinds; some appear to have been produced by small reptiles and crustaceans; but the principal markings are referable to some large quadruped, in which the fore-feet were much smaller than the hinder (Lign. 132). From the supposed resem

blance of these imprints to the shape of the human hand, the name of Chirotherium was adopted to designate the animals which left these enigmatical "footsteps on the sands of Time." Since the discovery of the bones of gigantic Sauro

2

LIGN. 132.-NATURAL CASTS OF THE FOOT-MARKS OF THE LABYRINTHODON (CHIROTHE RIUM) AND CASTS OF SUN-CRACKS, ON SANDSTONE; FROM HILDBURGHAUSEN.

Fig. 1, 1, Impressions of the hinder feet. 2, 2, Imprints of the fore feet.
(One-eighth the natural size.)

[The imprints in this example are not right and left, but are parts of two tracks.]

batrachians in the same strata, it has been suggested that the footmarks were produced by some of the large Labyrinthodons; a conjecture highly probable, for the fore and hind feet of many of the frog-tribe are as dissimilar in size as those of the so-called Chirotherium.*

15. ORNITHOIDICHNITES, OR FOSSIL FOOTPRINTS RESEMB- In the United States of North America, a group of strata, which, as far as the imperfect

LING THOSE OF BIRDS.

* See Dr. Buckland's "Bridgewater Treatises" for figures and further details. A fine series of specimens of Chirotherian imprints are in the Brit. Mus. Collect. Petrifactions, p. 63. See also Geol. Transact. 2 ser. vol. vi. p. 537, and Geol. Soc. Journ. vol. ix. p. 37.

evidence afforded by their fossils can show, appear to belong to the Triassic system, occur in the valley of the Connecticut river, stretching through the states of Connecticut and Massachusetts; and a band of similar deposits ranges from beneath the Palisadoes of the Hudson to the interior of Virginia.* The materials are red shale and argillaceous sandstone, with detached beds of conglomerate.† It is on the surface of the laminated argillaceous sandstones of this system, and principally in the valley of the Connecticut, that occur those mysterious characters on which the sagacity and unremitting labours of Professor Hitchcock have thrown so much light; ‡ but still the nature of the animals by which the foot-prints were made is involved in obscurity, for no vestiges of the skeletons of the bipeds, the lineaments of whose feet are so vividly apparent, have been discovered.§

The origin assigned to these markings was for a long while disputed, but Professor Hitchcock's interpretation is now generally admitted;

* When the fossils of these Virginian sandstones, shales, and coal-beds are taken in consideration, the peculiar group of strata above alluded to must be regarded as having much of the character of the Lower Jurassic series of the North British area. See above p. 519.

† Professor Henry Rogers' Address at the Meeting of the Association of American Geologists, May, 1844.

The reader is referred to Professor Hitchcock's "Report on the Geology of Massachusetts," to Dr. Buckland's " Bridgewater Treatise," to the "American Journal of Science," Transact. Americ. Phil. Soc. new ser., and Trans. Amer. Acad. Arts and Sciences, for many interesting papers by Dr. Deane (who first drew Professor Hitchcock's attention to the subject) and other American naturalists; and to the "Medals of Creation," p. 768; and "Petrifactions," p. 64.

§ Reptilian remains occur in the Red Sandstones of North America, (namely, the Clepsysaurus, Centemodon, and Bathygnathus, Geol. Soc. Journ. vol. xii. p. 377). Dr. Emmons has described the bone of a bird from the Chatham coal-field, in Carolina, probably of nearly the same age; and numerous relics of reptiles (Dictyosaurus, Omosaurus and Rutiodon or Clepsysaurus, and Compsosaurus or Palæosaurus), and some small Mammalian jaws from beds of Permian (?) age. Americ. Geol. part vi. 1857.

though the discovery of bones of birds in strata of this epoch is required before the question can be regarded as determined. The number and variety of these footsteps are so considerable, that in 1853 Professor Hitchcock considered he had sufficient data to warrant their arrangement in numerous genera, comprising upwards of fifty species, varying in size from half an inch to twenty inches in length; the greater part being referable to bipeds; whilst about a dozen quadrupeds can be recognised, most of them with the hind-feet much larger than the fore-feet.* The abundance of foot-prints on the Connecticut sandstones is explained by supposing the strata to have originated from sediments deposited in a tidal estuary; and that various kinds of birds and reptiles frequented the low muddy shores, when the tide receded, in pursuit of worms and other prey; and that their footsteps were covered with a thin layer of silt at each reflux of the waves.

toes

The following remarks of Dr. Deane will convey an idea of the colossal proportions of some of these imprints:-"I have in my possession consecutive impressions of a tridactylous foot which measures eighteen inches in length, by fourteen in breadth, between the extremities of the lateral Each step will hold half a gallon of water, and the stride is four feet." The original bird must have been " four or five times larger than the African Ostrich, and, on this basis, could not have weighed less than 600 pounds . . . . . Every step the creature took sank deep into the stratum, and the sub-strata bent beneath the enormous load. If an ox walk over stiffened clay, he would not sink so deeply as did this mighty bird." t

66

Sir C. Lyell mentions having seen on the banks of the Connecticut river (at Smith's Ferry, near Northampton, eleven miles from Springfield) a space several yards square where the entire surface of the shale was irregular and jagged, owing to the number of footsteps, not one of which could be traced distinctly, as when a flock of sheep have passed over a muddy road; but, on withdrawing from this area, the confusion gradually ceased, and the tracks became more and more distinct."

Some fine slabs of the sandstone, covered with several tracks of bipeds of various sizes, collected by Dr. Deane, are deposited in the British Museum. A representation of

* See "Final Report on the Geology of Massachusetts," p. 477; "Elementary Geology," p. 155; and "Geology of the Globe," p. 98. † Boston Journal of Nat. Hist. vol. v. p. 282.

Travels in North America, vol. i. p. 254.

one of the small imprints of the natural size, with the surface of the stone marked with hemispherical pits produced by a shower of rain, is given in Lign, 133.

Sandstone; Massachusetts (nat. size).

[American Journ. Science, vol. xlvi. p. 73.]

The enormous magnitude of some of the foot-prints was formerly deemed an insuperable objection to the interpretation of these obscure vestiges adopted by the American naturalists; but the discovery of the bones of tridactyle birds (Moa, see p. 129) in the alluvial deposits of New Zealand, some of which indicate a size equal to that of the most colossal of the fossil imprints, has removed that objection, and shown that in comparatively modern times, the