An entire skull of the largest species discovered in the new red sandstones of Wurtemberg; a lower jaw of the same species found in the same formation in Warwickshire; some vertebræ, and a few fragments of bones of the limbs, have served, with the indications of size and shape of the trunk of the animal yielded by the series of consecutive foot-prints, as the basis of the restoration of the Labyrinthodon salamandroides, in the Secondary Island. It is to be understood, however, that, with the exception of the head, the form of the animal is necessarily more or less conjectural.
Nos. 19 & 20.—Labyrinthodon pachygnathus.
This name, signifying the Thick-jawed Labyrinthodon, was given by its discoverer to a species of these singular Batrachia, found in the new red sandstone of Warwickshire, and which bears to the largest species the proportion exhibited by the head and fore-part of the body, as emerging from the water, for which parts alone the fossils hitherto discovered justify the restoration.[6]
Nos. 19 & 20. Section of Tooth of Labyrinthodon.
a Pulp-cavity: b b inflected folds of ossified capsule of tooth.
Nos. 21 & 22.—Dicynodon.
In 1844 Mr. Andrew G. Bain, who had been employed in the construction of military roads in the colony of the Cape of Good Hope, discovered, in the tract of country extending northwards from the county of Albany, about 450 miles east of Cape Town, several nodules or lumps of a kind of sandstone, which, when broken, displayed, in most instances, evidences of fossil bones, and usually of a skull with two large projecting teeth. Accordingly, these evidences of ancient animal life in South Africa were first notified to English geologists by Mr. Bain under the name of “Bidentals;” and the specimens transmitted by him were submitted at his request to Professor Owen for examination. The results of the comparisons thereupon instituted went to show that there had formerly existed in South Africa, and from geological evidence, probably, in a great salt-water lake or inland sea, since converted into dry land, a race of reptilian animals presenting in the construction of their skull characters of the crocodile, the tortoise, and the lizard, coupled with the presence of a pair of huge sharp-pointed tusks, growing downwards, one from each side of the upper jaw, like the tusks of the mammalian morse or walrus. No other kind of teeth were developed in these singular animals: the lower jaw was armed, as in the tortoise, by a trenchant sheath of horn. Some bones of the back, or vertebræ, by the hollowness of the co-adapted articular surfaces, indicate these reptiles to have been good swimmers, and probably to have habitually existed in water; but the construction of the bony passages of the nostrils proves that they must have come to the surface to breathe air.
Some extinct plants allied to the Lepidodendron, with other fossils, render it probable that the sandstones containing the Dicynodont reptiles were of the same geological age as those that have revealed the remains of the Labyrinthodonts in Europe.
The generic name Dicynodon is from the Greek words signifying “two tusks or canine teeth.” Three species of this genus have been demonstrated from the fossils transmitted by Mr. Bain.
The Dicynodon lacerticeps, or Lizard-headed Dicynodon, attained the bulk of a walrus; the form of the head and tusks is correctly given in the restoration (No. 21); the trunk has been added conjecturally, to illustrate the strange combination of characters manifested in the head.