1833.] EXTINCT QUADRUPEDS. 59 



The plain, at the distance of a few miles from the coast, belongs to 

 the great Pampean formation, which consists in part of a reddish clay, 

 and in part of a highly calcareous marly rock. Nearer the coast there 

 are some plains formed from the wreck of the upper plain, and from 

 mud, gravel, and sand thrown up by the sea during the slow elevation of 

 the land, of which elevation we have evidence in upraised beds of recent 

 shells, and in rounded pebbles of pumice scattered over the country. 

 At Punta Alta we have a section of one of these later-formed little plains, 

 which is highly interesting from the number and extraordinary character 

 of the remains of gigantic land-animals embedded in it. These have 

 been fully described by Professor Owen, in the Zoology of the voyage 

 of the Beagle, and are deposited in the College of Surgeons. I will here 

 give only a brief outline of their nature. 



First, parts of three heads and other bones of the Megatherium, the 

 huge dimensions of which are expressed by its name. Secondly, the 

 Megalonyx, a great allied animal. Thirdly, the Scelidotherium, also an 

 allied animal, of which I obtained a nearly perfect skeleton. It must 

 have been as large as a rhinoceros: in the structure of its head it 

 comes, according to Mr. Owen, nearest to the Cape Ant-eater, but in 

 some other respects it approaches to the armadilloes. Fourthly, the 

 Mylodon Darwinii, a closely related genus of little inferior size. Fifthly, 

 another gigantic edental quadruped. Sixthly, a large animal, with an 

 osseous coat in compartments, very like that of an armadillo. Seventhly, 

 *n extinct kind of horse, to which I shall have again to refer. Eighthly, 

 a tooth of a Pachydermatous animal, probably the same with the 

 Macrauchenia, a huge beast with a long neck like a camel, which I 

 shall also refer to again. Lastly, the Toxodon, perhaps one of the 

 strangest animals ever discovered : in size it equalled an elephant or 

 megatherium, but the structure of its teeth, as Mr. Owen states, proves 

 indisputably that it was intimately related to the Gnawers, the order 

 which, at the present day, includes most of the smallest quadrupeds : 

 in many details it is allied to the Pachydermata : judging from the 

 position of its eyes, ears, and nostrils, it was probably aquatic, like the 

 Dugong and Manatee, to which it is also allied. How wonderfully are 

 the different Orders, at the present time so well separated, blended 

 together in different points of the structure of the Toxodon 1 



The remains of these nine great quadrupeds, and many detached 

 bones were found embedded on the beach, within the space of about 200 

 yards square. It is a remarkable circumstance that so many different 

 species should be found together ; and it proves how numerous in kind 

 the ancient inhabitants of this country must have been. At the distance 

 of about thirty miles from P. Alta, in a cliff of red earth, I found several 

 fragments of bones, some of large size. Among them were the teeth 

 of a gnawer, equalling in size and closely resembling those of the 

 Capybara, whose habits have been described ; and therefore, probably, 

 an aquatic animal. There was also part of the head of a Ctenomys ; 

 the species being different from the Tucutuco, but with a close general 

 resemblance. The red earth, like that of the Pampas, in which these 

 remains were embedded, contains, according to Professor Ehrenberg, 



