not impede its movements in the water. Living on herbs, they would serve as huge hooks by which it tore up the aquatic vegetation. And, as Buckland has suggested, "the tusks may also have been applied with mechanical advantage to hook on the head of the animal to the bank, with the nostrils sustained above the water so as to breathe securely during sleep, whilst the body remained floating at perfect ease beneath the surface. The animal might thus repose, moored to the margin of the lake or river, without the slightest muscular exertion, the weight of the head and body tending to fix and keep the tusks fast anchored in the substance of the bank; as the weight of the body of a sleeping bird keeps the claws clasped firmly around its perch." The length of Dinotherium giganteum must have exceeded eighteen feet. In the uppermost layers of the tertiary the remains of extinct animals, equally novel and interesting, have been met with. The condition of these remains, and, generally, the character of the deposits in which they are found em bedded, have raised the sud question, May these mammals not have witnessed the introduction of the present epoch? But before a definite answer can be rendered to this ques-to tion, much more informa Fig. 46. tion must be obtained as doodt 20 to the phenomena of cli-la mate, of the physical con- do dition of the earth, &c., in connection with which the pleistocene strata were laid down, than we at present possess. The countries into which these huge mam mals, which press so closely Skeleton of Megatherium. on Adamic times, are the found, suggested to Professor Owen, nearly twenty years ago, likelihood that, "in the highest organized class of animals the same forms were restricted to the same great provinces at pliocene periods as they are at the present day." Even at the time this suggestion was made there were many exceptions to it; and since that time the geogra phical range of many forms has been greatly enlarged. Many which were then regarded as limited to comparatively small areas, are now found to be cosmopolites. It is, nevertheless, instructive to notice that in such an example as the Megatherium, the area over which it roamed in the pre-Adamic epoch corresponded generally with that in which the recent mammals which bear the closest structural affinities to it are to be found; as, for example, the Sloths and Armadilloes on the one hand, and the Ant-eaters on the other. The size of the Megatherium of the upper tertiary deposits of South America, is at once seen, when we compare the measurements of its skeleton with those of the skeleton of a large Hippopotamus. The length of the former from the tip of the nose to the end of the tail is eighteen feet two inches; and that of the latter is eleven feet two inches. The height of the former, from the sole of the front feet to the top of the shoulder, is seven feet two inches; and that of the latter five feet six inches. The illustrations of the wisdom of the Creator to be met with in the structure of this huge mammal, supply peculiarly rich themes for the student of natural theology. The principle of the correlation of animal structures, which Baron Cuvier made such admirable use of in paleontology, is well seen in the examination of the skeleton of the Megatherium. In rebuilding extinct species from the scattered bones of the upper tertiaries, Cuvier laid it down as a law, "that every organized body forms a whole, a single circumscribed system, the parts of which mutually correspond and concur to the same definite action. and reaction. None of these parts can change without the others also changing, and consequently each part, taken separately, indicates and gives all the rest." The application of this principle, first by Cuvier, and afterwards by Owen, Falconer, and others, has led to most interesting and valuable results. In specimens even in which many of the bones are still amissing, the building up of the animal has not been hindered; and a mere fragment of bone has been sufficient to indicate the size, the structure, and the habits of the beast or bird to which in pre-Adamic times it belonged. And, as in the case of the Megatherium, the organization of the bony skeleton has suggested to the scientific inquirer the climatology of the regions in which it lived, and the character of the vegetation which served for its support. The Mastodon and the Mammoth were other two of the great mammals of the newer tertiary periods. They belonged to the Elephant family. The former, which takes its name from the teat-like form of its teeth, appears to have been very generally distributed over the world. The most complete skeleton which has been found is that of the species Turicencis, which was dug up some years ago from pliocene deposits in Piedmont. The length of this species, from the tail to the end of the tusks, is seventeen feet. "The Mastodons," says Owen, "were elephants with the grinding teeth less complex in structure, and adapted for bruising coarser vegetable substances." When the bones of the Mastodon were first discovered, they gave rise to speculations and theories of the most extravagant and absurd kind. It was, for example, very generally believed that these were the bones of the antediluvians mentioned in Genesis vi. 4.-"There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.' But the form which brings the pre-Adamic period into closest relation with the present epoch, is that known as the Mammoth or Elephas primigenius. Some have held that it was characteristic equally of the former and of the latter epochs. Many links yet missing must be found, before we can be warranted to hold such an opinion. An entire specimen, which is now in the museum at St. Petersburg, was discovered at the mouth of the river Lena in Siberia. The Mammoth was covered by a reddish wool and black hairs. Its length, from the nose to the end of the tail, was about seventeen feet; its height was above nine feet; and measuring the tusks along their beautiful curve, they were nine feet six inches long. The principal object in view in the preceding sketch has been to furnish a plain and a sufficiently definite account, both of the order of strata and of the succession of life on the earth. The following diagram (Fig. 48, p. 33) has been constructed in order to present to the eye of the reader the results of the foregoing statements. It has already been pointed out, that the principal matters of controversy regarding the earth are to be found in connection with the lowest rocks with which we are acquainted, and with the deposits which are met with at the close of the tertiary system. These must now be considered. Under the term Pleistocene is included what is known as the seem to have been deposited. This period has been held by many to harmonize with the chaos alleged to be described in the opening verses of Genesis. This leads us to the threshold of the " theories of creation" which are to be examined. There are still, however, several topics to be looked at before these can be profitably expounded. We have seen that the surface of the earth is not now in its natural condition. It has been disturbed and broken by many agencies. Had the stratification observable in all the rocks which have been formed by the gradual deposition of earthy matter at the bottom of the sea, in lakes, in deltas, in the channels of rivers, and on land, not been inter Fig. 50. fered with, it would in every case have been horizontal-that is, if the earthy matter was laid down on a bed in a line with the horizon. If not, under the direction of well known laws, inequalities would be filled up, and the stratification would ultimately show an unbroken level-it would become horizontal. This is not now the case in any but in the uppermost members of the last tertiary deposits. |