The Labyrinthodons.
Let us now return to the Plateau, from whence we can obtain the best view of the islands and their singular tenants. Before describing them, however, we will remind the visitor that the lowest or oldest rocks, which we have shown him, were the old red sandstone; next above them were the carboniferous limestone, the millstone grit, the coal-measures, and then the new red sandstone. It is with this last formation that the restorations of the extinct animals commence. Before that period fossil remains indicate that fish inhabited the waters of the earth, but there are no traces of the existence of any reptiles or higher animals. Reptiles first appear in the new red sandstone, and as the extreme right of the islands is arranged to represent this formation, it is there that we shall find the Labyrinthodon and the Dicynodon, of each of which there are two species. The strata which overlie the new red sandstone will be now mentioned in the order of their super-position, each successive formation bringing us nearer to the forms of animal life which are at present living upon the earth.
Next above the new red sandstone comes the lias, the general direction of the inclination of the beds being the same as in the coal-cliff, and the newer beds covering up the old ones as we advance in the direction of the larger islands. The lias animals are here represented by three very dissimilar forms; there are three species of Ichthyosaurus, or Fish Lizard; three species of Plesiosaurus, or Serpent Lizard, and a crocodilian beast called Teleosaurus, which much resembles the fish-eating Gavial of the river Ganges. This crocodile and the fish lizards formerly inhabited the neighbourhood of Whitby in Yorkshire, where their remains are found in good condition. Dr. Buckland describes the Plesiosaurus as the most singular and monstrous of the relics of the former world, having the head of a lizard, the teeth of a crocodile, a neck like the body of a serpent, the trunk and tail of an ordinary quadruped, the ribs of a chameleon, and the paddles of a whale.
The next formation in ascending order is the oolite. To this stratum, as well as to the succeeding one, belongs the Megalosaurus, or Gigantic Lizard, which measures 39 feet from snout to top of tail, and 22 feet 6 inches round the body, and the smaller Pterodactyles.
Still proceeding to the left, we pass next to the Wealden formation so well known in Kent, Surrey, and Sussex. Here we see the gigantic Iguanodons, and the Hylæosaurus, or Great Spiny Lizard of the Wealden. It is with these creatures that the name of the late distinguished palæontologist, Dr. Mantell, will ever be connected, since to his labours in Tilgate Forest and other parts we are indebted for our knowledge of these animals.
Above the Wealden formation come those of the lower greensand and the chalk. Both of these also contain fragments of singular reptiles of large size, the Mosasaurus and great Pterodactyles (most probably the fabled dragon of old) restored from Mr. Bowerbank’s specimens.
With these we quit the Secondary Island, and may next turn our attention to the island beyond, which contains the principal forms characterising the strata belonging to the tertiary period. Hitherto we have shown the visitor nothing but reptiles—now, upon the Tertiary Island, he will find a higher order of animal life, and meet with forms more nearly resembling our living animals. Next in procession are the animals restored by Baron Cuvier from fragments found in the Gypsum beds of the Paris basin: the Palæotherium, or Ancient Beast, might be justly called the first triumph of comparative anatomy, as from a few detached pieces of bone Cuvier was enabled to construct the entire animal, which, by his drawings, appears to have resembled the Tapir of the present day. After these come the more elegant pachydermatous animal called the Anoplotherium commune and the Anoplotherium gracilis, and not far off we see the Megatherium, or Gigantic Sloth, in the act of pulling down a tree to obtain the leaves, upon which it was accustomed to feed, as its smaller analogies do at the present day. These, with the Irish Elks, first found in the Isle of Man, are grouped upon this island, and present a scene equally remarkable and instructive to all those who are interested in the natural history of the earlier periods of the earth.
Great Pterodactyles.