was thus enabled to strip off the leaves and smaller branches, which the absence of teeth in the front of the jaw left to be performed by such agency. Every contrivance was introduced to fit these animals for the performance of certain offices in the ancient forests of South America, which are now executed by a multitude of smaller animals, not very dissimilar in many points of structure.

The megatheroid animals, however, are not the only gigantic species of the edentate order living at this period. Associated with them was an armadillo, almost as colossal in its proportions and quite as anomalous in its structure. This animal has been called the Glyptodon,* and it exhibits in the complicated structure of its teeth an approach rather to the pachydermatous type shewn in the Toxodon than to the megathere or the existing armadilloes, while in other respects it seems to have connected the edentates with the heavy-coated rhinoceros.

The Glyptodon, like the armadillo, was covered and defended by a shell not unlike a coat of mail, made up of round or many-sided pieces, fitting one another accurately, continuous over the whole of the upper part of the body, and covering the upper surface of the thick and powerful tail. The armour is massive and very heavy, and when detached from the body resembles a barrel.

The bones of the leg and foot, perfectly adapted to bear the steady pressure of an enormous weight, are extremely interesting. They present the framework of a foot of such structure and form as is without a parallel in the animal kingdom, so admi

* гUπтоL (glyptos), sculptured; odovs (odous), tooth.

rably is it contrived to form the base of a column destined to support a vast superincumbent weight, and at the same time to allow of that degree of motion of the fore extremities which is required for the scratching and digging operations of animals like armadilloes. The Glyptodon can only be matched

Fig. 147

GLYPTODON.

by the great land tortoise, whose remains are found fossil in the Sewalik Hills; and we may almost consider it to have represented this monster, performing a nearly similar part, and clearing away the decaying animal and vegetable matter, that might otherwise have accumulated and become mischievous. Several species of gigantic size have been determined from the examination of fossils brought to England, and now preserved either in the British Museum or the Royal College of Surgeons.

The inhabitants of the central plains of South

America during this period appear to have wandered northwards as far as the southern districts of North America, while the Mastodon of the countries ranged southwards into Brazil. Whether the means of passage consisted of continuous or broken land on the eastern side of the Gulf of Mexico, or whether the high land of Mexico itself even then connected the two continents, we are not at present able to tell, but the very broad distinctions that there are between the extinct faunas of this comparatively modern period, as exhibited by the fossils of North and South America generally, as well as the great difference observable in the recent faunas, would rather lead us to conjecture that the species common to both may have been conveyed accidentally, and that these two great tracts of land in the western hemisphere were anciently detached from one another.

However the case may have been in that respect, it is interesting to consider the condition of this part of our earth at the period immediately antecedent to the introduction of man. Instead of a country remarkable for the absence of all large quadrupeds, it was exactly the reverse, but these ancient giants are now represented by smaller although similar species. The Pampas then, perhaps, presented a condition of vegetation little different from that still characteristic of them; numerous clumps of forest trees were dotted about at intervals, and the intervening country was covered for the most part by rich and luxuriant vegetation. Other trees probably fringed the margin of those gigantic rivers which still pour out their torrents of water and drain a mighty continent. In the half swampy tracts, or in the

pools formed by the shifting beds of these rivers, the Toxodon then dwelt; and over the broad plains the Macrauchenia slowly paced. At one spot, numerous bare trunks of trees, stripped of their verdure, rotten and half decayed, or alive again with the busy tread of millions of ants and other insects, mark the vicinity of the great leaf-eating tribe. The Glyptodon, with his heavy tread, slowly advances under the weight of a thick and cumbrous coat of mail, and finally clears away the half-destroyed vegetation. The smaller species of the megatheroid family—each one, indeed, a giant in his way-feed on the younger and smaller plants, tearing them up by the roots or reaching from the ground to devour their foliage.

But presently the Megatherium himself appears, toiling slowly on from some great tree recently laid low and quite stripped of its green covering. The earth groans under the enormous mass; each step bears down and crushes the thickly growing reeds and other plants; but the monster continues to advance towards a noble tree, the monarch of this primæval forest. "For a while he pauses before it, as if doubting whether, having resisted the storms of so many seasons, it will yield even to his vast strength. But soon his resolution is taken. Having set himself to the task, he first loosens the soil around the tree to a great depth by the powerful claws on his fore-feet, and in this preliminary work he occupies himself for a while and now observe him carefully. Marching close to the tree, watch him as he plants his monstrous hind feet carefully and earnestly, the long projecting claw taking firm and deep hold of the ground. His tail is so placed as to rest on the ground and sup

port the body. The hind legs are set, and the animal, lifting itself up like a huge kangaroo, grasps the tree with its fore-legs at as great a height as possible, and firmly grapples it with the muscles of the trunk, while the pelvis and hind limbs, animated by the nervous influence of the unusually large spinal cord, combine all their forces in the effort about to be made. And now conceive the massive frame of the Megatherium convulsed with the mighty wrestling, every vibrating fibre reacting upon its bony attachment with the force of a hundred giants: extraordinary must be the strength and proportions of the tree, if, when rocked to and fro, to right and left, in such an embrace, it can long withstand the efforts of its assailant." (Owen, on the Mylodon.) The tree at length gives way; the animal, although shaken and weary with the mighty effort, at once begins to strip off every green twig.

The effort, however, even when successful, was not always without danger.* The tree in falling would sometimes by its weight crush its powerful assailant, and the bulky animal, unable to guide it in its fall, might often be injured by the trunk or the larger

* In the specimen of Mylodon, in the College of Surgeons, the skull has undergone two fractures during the life of the animal, one of which is entirely healed and the other partially. The former exhibits the outer tables broken by a fracture four inches long, near the orbit. The other is more extensive, and behind, being five inches long, and three broad, and over the brain. The inner plate has in both these cases defended the brain from any serious injury, and the animal seems to have been recovering from the latter accident at the time of its death. (See Professor Owen's memoir "On the Mylodon," &c., p. 22, et passim. Many of the remarks in the present chapter have been borrowed from this admirable monograph.)