pressed it, which I regard as very important. He at once exhibited to me a drawing of the foot of a recent Batrachian, the Alytis obstetricans, in a paper by Dr. Carl. Vogt, while the animal was in an embryo state. This drawing, which I have copied on fig. 3, shows the condition of the forefoot while yet ossification

was in an incipient state, or had not begun. The resemblance is certainly rather striking between this sketch and that on fig. 1: and it leads to the suspicion that some of the tubercular impressions of the track may have been made by the metacarpal bones. Such I suppose to be the character of a, a, a, a, fig. 3; and when these were fully ossified, it is easy to conceive that they might have been anchylosed into the structure in fig. 1, A.

Professor Agassiz stated a principle of comparative anatomy, in conversation on this subject, which is highly important, viz. that the structure of adult fossil animals, that lived as early as the new red sandstone period, corresponds more nearly with the embryonic structure of existing animals than with their adult development. Taking this principle in connection with the above drawing of the embryo-frog's foot, we are led to the conclusion, that the animal which made these huge footmarks was probably a Batrachian.

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It may seem a strong objection to such a conclusion, that the animal was a biped: for what an anomalous being would a biped frog be, with feet twenty inches long! And yet there is one genus of living biped Batrachians, including the Siren lacertina of Linnæus; and its feet have four toes in one species, and three in another. True, these animals have an enormously long tail dragging behind. Yet it is not improbable, that in the new red sandstone period, their bodies may have been more like that of a bird and such must have been essentially their form in order to have produced the row of tracks exhibited on fig. 1. That biped Saurians existed in the new red sandstone period, we know from the case of the Rhyncosaurus: and the Pterodactyl probably walked for the most part upon two legs. And it is quite as easy to admit the existence of biped Batrachians as biped Saurians. There is also reason to suppose, that some of these animals may have been somewhat intermediate in their characters, and have exhibited, like the Rhyncosaurus and Pterodactyl, a structure now found only in several classes of animals.

Genus OтOZOUM, (10s, the giant Otus, and Zwor.)

Foot tetradactylous, pachydactylous; toes all directed forward : the inner one shortest; the second longer, and the third the longest; the fourth but little shorter: all making distinct tuberclelike phalangeal impressions, the inner toes most so. Phalangeal impressions on mud, three by the inner toe, four by the second, and three by the two outer toes. Two bones of the metacarpus, articulated to the phalanges of the two outer toes, make a distinct impression. Cushion beneath the carpus arching downward, and sloping upward posteriorly. Animal bipedal.

* Cuvier, Règne Animal, Tome ii, p. 120.

Remarks. It may be that what I have reckoned as the first phalangeal impression on the two inner toes was made by metacarpal bones: and it is also possible, on the other hand, that both the impressions which I have described as having a metacarpal origin on the two outer toes, may have been phalangeal. Otozoum Moodii. (Fig. 1, A.)

Divarication of the outer toes, 35°; do. of the inner and second toe, 15°; do. of the outer and third toe, 12°; do. of the two middle toes, 5°. Length of the inner toe, 8.5 inches; do. of the second toe, 10-25 inches; do. of the third toe, 8 inches; do. of the outer toe, 8.5 inches; do. of the foot, 20 inches; do. of the step, about three feet. Distance between the extremities of the outer toes, 13 inches. Width of the foot behind the phalanges and metacarpus, 5 inches; do. of the toes, from 2 to 3.25 inches. Length of the phalanges of the inner toe :-proximal phalanx, 3 inches; of the second, 2 inches; of the third, 3.4 inches (?) do. of the second toe:-proximal, 2-4 inches; second, 2.5 inches; of the third, 2.9 inches; do. of the fourth, 2.6 inches (?); do. of the proximal metacarpal bone of the third and fourth toes, 3.5 inches; of the second, 4 inches: of the first phalanx of the third toe, 2 inches; of the second, 2 inches; of the distal, 3-8 inches (?); do. of the outer toe :-proximal, 16 inch; of the second, 1.6 inch; of the distal, 5-4 inches (?) Divarication of the axes of the feet, 30°. Distance to the right and left of the middle of the heel, from the average line of direction along which the animal moved, 2.5 inches. Integuments of the bottom of the foot, rugose and irregularly papillose.

Distinctive Characters.-Four thick toes directed forward and making strong phalangeal impressions, distinguish this animal from all others that have left their footprints in the sandstone of New England. The number of phalanges, also, in the toes, separates it from every other. As only one of the tracks of the animal is entire enough for description, I should have suspected some deception in both these characteristics; but sufficient remains of the other tracks, to identify them by their repetition; particularly in respect to the phalangeal impressions of the two

outer toes.

Situation and character of the Deposits containing these tracks. The tracks above described are all in relief, and the rock is a very coarse gray sandstone, the grains being often as large as buckshot. Yet every thing is exhibited most distinctly. Nearly the whole slab is covered with rain drops most beautifully exhibited, and shown upon the drawing, fig. 1. The tracks appear to have been made upon a fine micaceous sand, which has little more coherence now than when the animals trod upon it. But the coarse material that was subsequently brought over this fine

stratum, seems to have adapted itself to every irregularity, and now presents us with perfect casts of the original tracks, while the subjacent rock, which seems to have been a good moulding sand, does not hold together enough to show a single entire track.

It seems that the rows of tracks at this locality were parallel to the edges of the water. They run nearly east and west, and in the direction of the strike of the strata; and in one or two places upon the slab figured above, we can see where the water acted by gentle undulations upon the fine micaceous sand, and upon the coarse grit, partially wearing them both away, or intermixing them; and some of the large tracks look as if the sand had been so wet that the impressions were partly filled up by the sand sliding into them. Only the second track exhibits the outlines of the parts entire. On that, the protuberances rise from one to two inches above the general surface. The extremities of this track have been broken off accidentally, except the inner one which is obscured by lying too near the edge of the water. It is obvious however how far it extended. As I have before mentioned, the second large track on fig. 1, forms the type by which I have restored the others, or rather, completed them; for some of the toes remain in all cases, and so far as they go, they confirm the characters exhibited by the second. It is only a part of the phalangeal impressions that shows the rugosities or papillæ of the skin: yet I can hardly doubt but we have them exhibited on some of the protuberances.

All the left-hand side of the slab, represented on fig. 1, for about half its length, embracing the first two of the large tracks, has been split off an inch or two lower than the other part of the slab. This makes no difference in the large tracks, except to make them stand out in higher relief; but it brings to light several of the smaller tracks, which, although of the same species, must have been impressed at a later period-probably one or two years later than those scattered among the rain drops.

I have not been able to find any certain example of claws upon the large tracks. Most of the toes are somewhat mutilated at their extremities; and in general, the sides converge rapidly on the last phalanx, so that if claws existed on the foot-and I think they did they must have been short and blunt.

Circumstances under which the tracks of these animals were made. Have we any facts in this case indicating the circumstances under which these tracks were made and preserved? It is difficult, without a sketch of the topography of the region, to convey an adequate idea of their situation. The spot is on the south side of Mount Holyoke, which here runs nearly east and west. It curves southerly, however, as it crosses the river, and on the west we have Mount Tom, as the continuation of Holyoke is called. On the east we have a primary range at a short

distance, against which the east end of Holyoke abuts, with only a narrow space between. It is obvious then, that this locality must have been the north shore of an estuary, opening southerly, and extending to what is now Long Island Sound. That it was salt-water is evident from the occurrence of fucoids in the same basin, a few miles south. Now we know that the current through this estuary was either north or south, for the ripple marks have an east and west direction, and in size they correspond with those made by the waters of the Connecticut on the sand in the same region. The direction of that stream also is south; and some have thought that the floods of that stream may have brought in the sand which filled the tracks. But the locality must have been defended from a northerly current by Mount Holyoke, whose elevation doubtless formed the shore on which the animals trod. Indeed, it would be exposed to no current that I can conceive of, sufficiently powerful to move such coarse materials, except the waves and tides from the south. And yet, a deposit at least six inches thick of coarse sand, was brought in over the tracks. It seems difficult to conceive how any river floods should have raised the waters of an estuary enough for this purpose; and more difficult to show how these coarse materials could have been thus brought over this spot. I have hence been rather inclined to suppose that they were silted in by the waves and the tides:-not the daily tides, but the spring tides. Suppose the animals walked along the shore during neap tide, and that no rain fell till the return of spring tide. By that time the mud might have become so indurated, that even such coarse materials might have been brought in by moderate waves, without erasing the impressions. It might be also that the river, which doubtless flowed into this estuary, answering to the present Connecticut, was at the same time swollen; and perhaps also we must resort to the supposition of a subsidence of the localityan occurrence not uncommon during igneous eruptions: and we know from other circumstances, that the tracks were made about the same period in which Holyoke was erupted. We have evidence also that this period, including some precursory outbursts of the igneous matter, was quite long.

Should time and health permit, I hope to send another communication ere long, describing other new species of tracks in the Connecticut valley. I have no others, however, that are so remarkable as the large one herein described. This, indeed, seems to eclipse that of the Brontozoum (Ornithoidichnites) giganteum, figured in the Journal of Science for 1836, being even of greater dimensions. I had thought that we had reached nearly the end of this ancient volume; but it may be, that many new chapters will yet be brought to light, when its stony leaves shall be still farther opened.

SECOND SERIES, Vol. IV, No. 10.-July, 1847.

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