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Show 208 PATAGONIA. Jan. 1834. interrupted at long intervals by periods of repose. But we must now return to Port St. Julian. On the south side of the harbour, a cliff of about ninety feet in height intersects a plain constituted of the formations above described ; and its surface is strewed over with recent marine shells. The gravel, however, differently from that in every other locality, is covered by a very irregular and thin bed of a reddish loam, containing a few small calcareous concretions. The matter somewhat resembles that of the Pampas, and probably owes its origin either to a small stream having formerly entered the sea at that spot, or to a mud-bank similar to those now existing at the head of the harbour. In one spot this earthy matter filled up a hollow, or gully, worn quite through the gravel, and in this mass a group of large bones was embedded. The animal to which they belonged, must have lived, as in the case at Bahia Blanca, at a period long subsequent to the existence of the shells now inhabiting the coast. We may feel sure of this, because the formation of the lower terrace or plain, must necessarily have been posterior to those above it, and on the surface of the two higher ones, sea-shells of recent species are scattered. From the small physical change, which the last one hundred feet elevation of the continent could have produced, the climate, as well as the general condition of Patagonia, probably was nearly the same, at the time when the animal was embedded, as it now is. This conclusion is moreover supported by the identity of the shells belonging to the two ages. Then immediately occurred the difficulty, how could any large quadruped have subsisted on these wretched deserts in lat. 49° 15'? I had no idea at the time, to what kind of animal these remains belonged. The puzzle, however, was soon solved when Mr. Owen examined them; for he considers that they formed part of an animal allied to the guanaco or llama, but fully as large as the true camel. As all the existing members of the family of Camelidre are inhabitants of the most sterile countries, so may we suppose was this extinct kind. The structure of the cervical vertebrre, the transverse processes Jan. 1834. FOSSIL REMAINS. 209 not .b eing perforated for the vertebral artery' indicates its a:ffimty: some other parts, however, of its structure, pro-bably are anomalous. The. most important result of this discovery, is the confirmatwn of the law that existing animals have a close relation in form with extinct species. As the guanaco is the characteristic quadruped of Patagonia, and the vicuna of the sn~w-.clad . summ~ts of the Cordillera, so in bygone days, th1s gigantic species of the same family must have been conspicuous on the southern plains. We see this same relation of type between the existing and fossil Ctenomys, between the c~pyb~ra (but less plainly, as shown by Mr. Owen) and the. gigantic Tox?don; and lastly, between the living and extmct Edentata. , At the present day, in South America, there exist probably nineteen species of this order distributed into several genera; while throughout the :est of the world there are but five. If, then, there is a relation between the living and the dead, we should expect that the Edentata would be numerous in the fossil state. I need only reply by enumerating the megatheriurn, and the three or four other great species, discovered at Bahia Blanca · the remains of some of which are also abundant over the whol~ immense territory of La Plata. I have already pointed out the singular relation between the armadilloes and their great prototypes, even in a point -apparently of so little importance as their external covering. The order of rodents at the present day, is most conspicuous in South America, on account of the vast number* and size of the species, and the multitude of individuals : according to the same law, we should expect to find their representatives in a fossil state. Mr. Owen has shown how far the Toxodon is thus related; and it is moreover not tt .rn my collection Mr. Waterhouse distinguishes twenty-seven species of mlCe ; to these must be added about thirteen more, known from the works of Azara, and other naturalists ; so that we have forty species, which have actually been described as coming from between the Tropic and Cape Horn. VOL, III. P |