68

PRESIDENT JEFFERSON AND CUVIER. CHAP. III.

To proceed to the observation of President Jefferson on the Megalonix. Having found a bone which, by its articulating surface and general form, he recognised to be one of the finger bones of an animal of great size, he thought he had discovered that it must have carried a claw; and from that circumstance, again, he naturally enough concluded (on the principle-ex ungue leonem) that it belonged to a carnivorous animal. He next set about calculating the length of the supposed carnivorous claw, and from that to estimating the dimensions of the animal; and he satisfied himself that in this bone, a relic of the ancient world, he had obtained proof of the existence, during these olden times, of a lion of the height of the largest ox, and an opponent fit to cope with the mastodon.

But when the same bone came under the scrutiny of Baron Cuvier, his perfect knowledge of anatomy enabled him to draw a different conclusion. He first observed that in the middle of

the articulating surface there was a spine; in that respect it differed from the analogous bone in the feline tribe. He found no provision for the lateral attachment to the next bone; which we have just shown is necessary for the retraction of the claw. Then observing the segment of the circle which the bone described, he prolonged the line, and showed that the supposed claw must have been of such great length, that it could never have been retracted for the protection of its acute and curved point; and it would not have permitted the animal to put its foot to the ground. Pursuing the comparison, he rejected the idea of the bone belonging to an animal of the feline tribe at all. His attention was directed to another order of animals, the sloths, which are characterised by having long nails affixed to their toes. But in the sloth (p. 20) the nails are folded up in a different fashion from the claws of the lion; they just allow

the animal to walk, slowly and awkwardly, as if we were to fold our fingers on the palm of the hand, and bear upon our knuckles. On instituting a more just comparison, therefore, between this bone of the ancient animal and the corresponding bones of the sloth, Cuvier has satisfied us that the supposed enormous lion of the American President was an animal which scratched the ground, and fed on roots.

One experiences something like relief to find that there never existed such a huge carnivorous animal as that denominated megalonix.

These ungual bones, or bones of the claws, exhibit a remarkable correspondence with the habits and general forms of animals. Besides what we have seen in the lion or tiger, in the dog or wolf, in the bear and ant-eater, there is a variety, where we should least expect it, in those animals that live in woods, and climb the branches of trees. The squirrel, having his claws set both ways, runs with equal facility up and down the bole, and nestles in the angles of the branches of trees. The monkey leaps, and swings himself from branch to branch, and in springing, parts from his hold by the hinder extremities, before he reaches another branch with the anterior extremities; he leaps the intervening space, and catches with singular precision. But the sloths do not grasp; their fingers are like hooks, and their strength is in their arms; they do not hold, but hang suspended to the branch; they never let go with one set of hooks, until they have caught with the other; and thus they move along the branch, using both hind and fore feet over head, whilst their bodies are pendant. Here we see, once more, how the form of the extremities, the concentration of strength, and the habits of these animals, correspond not merely to their haunts in the forest, but to their mode of moving and living among the branches; all active, but in different manners.

Of late there have been deposited in our Museum in the College of Surgeons, the bones of an animal of great size; the examination of which affords an opportunity of applying the principles and mode of investigation followed by our great authority in this part of science. These remains consist of part of the head, spine, tail, pelvis; and the bones of one hinder extremity, and the scapula. Estimating the height of the animal to which they belonged at seven feet, it scarcely conveys an

adequate idea of its dimensions; for the thigh-bone is three times the diameter of that of the large elephant, in the same collection, and the pelvis or haunch-bone twice the breadth. If we form our opinion of its configuration on those principles to which we have had repeated occasion to refer, and judge of its strength by the size and prominence of the processes of these bones, we must conclude that the animal possessed extraordinary muscular power; and, directed by the same circumstances, we may obtain an idea of the manner in which that muscular power was employed.

On comparing these bones with drawings of the skeleton of the enormous animal preserved in the Royal Museum of Madrid, we see at once that they are parts of the remains of the great fossil quadruped of Paraguay, the Megatherium of Cuvier. And every observation of the form of the bones of the foot, the scapula, and the teeth, confirms the opinion which he entertained, that it was a vegetable feeder, and that its great strength was employed in flinging up the soil and digging for roots. Corresponding to the provisions in the bones of its feet. for sustaining enormous nails or claws, its immense muscular power seems to have been concentrated in its paws. I have heard it surmised that the animal may have sat upon its hinder extremities, and pulled down the branches of trees to itself, to feed upon them. It is only the great weight of its hind quarters that can countenance such an idea. We have not the humerus to declare, by the prominence and situation of its processes, which class of muscles of the arm were the most powerful; but as the scapula has the impression of a clavicle upon its acromion process, that enables us to form some conception of the extent of motion enjoyed by the anterior extremity; and from possessing the greater part of the pelvis, and the enormous bones of the posterior extremity, we can estimate the height, breadth, and strength of the whole animal. In short, judging from the bones that have been procured, we perceive that the muscular power of the Megatherium did not reside so much in the body (certainly not in the jaws) as in the extremities, and especially in the posterior extremities; and that its strength was given neither for rapidity of motion, nor for offence, but for digging.

How little was it to be expected that an alliance between a

part of anatomy so little valued as that of the bones, and mineralogy, should give rise to a new science!-that a department of natural history formerly pursued idly, vaguely, and somewhat fancifully, should henceforth, when thus associated with anatomy, be studied philosophically and inductively! It is both interesting and instructive to find relations thus established between branches of knowledge apparently so remotely connected.

In the true Amphibia, as the phoca (seal) and morse or walrus (sea-horse),

the feet are contracted, and almost enveloped in skin, the toes being webbed and converted into fins. We have sketched here the bones of the paddle of the walrus; and they are remarkably complete, considering the peculiar appearance of the feet in the living animal. The bones are accommodated to form

Part of Skeleton of Walrus.

an instrument for swimming; for these animals live in the water; they come to land only to suckle their young, or to bask in the sun; out of the water, they are the most unwieldy and helpless of all animals which breathe.

In the Cetacea-for example, the whales and dolphins-we see mammalia unprovided with hind feet. The scapula is large, the humerus very short, and the bones of the fore-arm and hand flattened and confined in membranes, which convert the anterior extremity into a fin. These animals, residing in the water, must rise to the surface to breathe. I need not say that in the dolphin (small bottle-nose whale) we recognise the bones of the anterior extremity, only a little further removed from the forms which we have been hitherto contemplating. The

seal and morse raise themselves out of the sea, and bask on the rocks: but the different species of dolphin continue always in the water ; the extremity is now a fin or an oar; and those who have seen the porpoise, or pelloch, (Scoticè,) in a stormy sea, must acknowledge how complete is the apparatus through which they enjoy their element.

The last examples I select shall be from relics of the ancient world.* These figures are taken from specimens, in the Museum of the College of Surgeons, of fossil animals of singular structure, between the crocodile and fish,-the ichthyosaurus Bones of Paddle and plesiosaurus. The skeletons are imbedded of Dolphin. in a calcareous rock; and are entire, but crushed, and a good deal disfigured. Here are only the extremities, or

paddles, consisting of a

multitude of bones arti

culated together: but

among these we still recognise the humerus, radius, and ulna, and

* The figure to the left is the anterior extremity of the Plesiosaurus; to the right, that of the Ichthyosaurus. In these paddles, we see the intermediate changes from the foot of animals to the fin of the fish-modifications of the fins of the walrus, dolphin, or turtle. We no longer discern the phalanges, or attempt to count the bones; they become irregular polygons or trapezoids-less like phalangeal bones than the radii of the fins of a fish. In fishes, the anterior extremity is recognised in the thoracic fin; and we may even discover the prototypes of the scapula and the bones of the arm connected with that fin.