| Fig. | 1.— | The cranium and part of the lower jaw. |
| 2.— | A portion of the skin, or dermal scutes, magnified. | |
| 3 and | 4.—Magnified figures of two teeth. |
The conclusions arrived at by the eminent comparative anatomists to whose examination the remains in question were submitted, show that the character of the fossils are those of Perennibranchiate Batrachians; that, with regard to the long bones, it is not improbable that the corresponding bones in the Archegosaurus ([p. 745]) and Labyrinthodon ([p. 741]) would present similar correspondences with those of the existing perennibranchiates; and that, although the Dendrerpeton cannot be referred to any known form of the two genera just mentioned, yet there exists strong evidence of its close affinity with these extinct Batrachians.
The Dendrerpeton Acadianum was probably between two and three feet in length. A series of minute biconcave vertebræ were found with the other remains in the erect tree, these, however, from their relatively small size, and from other characteristics, are regarded by Professor Wyman as having probably belonged to some other associated reptile.
The Labyrinthodont reptiles have been regarded as characteristic of the Permian and Triassic epochs, their remains being found in Germany and England in rocks of that age. The commencement of the existence of this family of sauroid-batrachians, however, is of greater antiquity, since their relics also occur in the formations of the Carboniferous epoch. The Archegosaurus ([p. 745]), a batrachian but slightly removed from the true Labyrinthodont type, has left its well-characterized remains in the Coal of Germany; the Parabatrachus, in that of Scotland; and the allied Dendrerpeton, in the Nova Scotian coal-field. This last-mentioned great carboniferous formation has, however, afforded fossil evidence of the existence of the true Labyrinthodonts in the Coal-period, for some cranial bones, imbedded in a mass of Pictou coal, lately sent to England by Mr. J. W. Dawson, and the subject of a Paper by Professor Owen, read before the Geological Society, were demonstrated by that distinguished palæontologist to have close affinity with the corresponding parts of the skull of the Triassic genera Capitosaurus and Metopias.
ICHNOLITES.
Ichnolites (Foot-prints on stone). [Lign. 245].—The sandstones and mud-stones of many localities retain the track-prints of animals that have passed along on the surface of the beds when in a soft state. These foot-prints, or ichnolites, either occur as impressions on the surface originally marked lay the animal in the act of progression, or as the reverse of such impressions, being casts in relief on the under side of the layer covering the surface originally impressed. Such indications of footsteps and trails have been noticed especially in the forest marble, a member of the Lower Oolite series, where Crustacea and Mollusks have left their markings, and in the New Red Sandstone, where the indications of reptilian quadrupeds and of bird-like bipeds[709] have been here and there preserved in great distinctness. Tracks referable to Crustaceans have been found by Mr. W. E. Logan, on the very ancient and rippled surfaces of the Potsdam Sandstone of North America (see [p. 543], note); and very lately Mr. J. W. Salter has communicated to the Geological Society the discovery of markings, referred by him to the little entomostracous Hymenocaris (see p. 526), on the Lower Lingula Flags of North Wales,—deposits of as great an age, if not older. The most ancient reptilian ichnolites are those discovered by Capt. L. Brickenden[710] in the Old Red, at Cummingston, near Elgin, which have some resemblance to the track of a club-footed Chelonian (Ly. fig. 521); and those of the Devonian sandstone of Sharp Mountain, Pennsylvania, discovered by Mr. I. Lea,[711] which exhibit distinct toes, and are probably allied to the Cheirotherian ichnolites, about to be mentioned, as are also other ancient fossil foot-tracks in the Carboniferous deposits[712] of Pennsylvania, which are figured and described in Ly. pp. 337-340.
[709] See Ornithoidichnites, in chap, xviii.
[710] Quart. Geol. Journ. vol. viii. p. 97, pl. iii.
[711] Across the ridges of the ripples on this slab is a narrow groove, passing along between the two rows of foot-prints; this might have been made by the body or the tail of the animal. Rep. Brit. Assoc. 1849, Sect. pp. 56 and 134; and Trans. Americ. Phil. Soc. new series, vol. x. part ii. plates xxxi. and xxxii.