V /^.YTLVCT QUADRUPEDS 87 



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 circum- 

 stance 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, eight 

 fresh-water and one salt-water infusorial animalcule ; therefore, 

 probably, it was an estuary deposit. 



The remains at Punta Alta were embedded in stratified 

 gravel and reddish mud, just such as the sea might now wash 

 up on a shallow bank. They were associated with twenty- 

 three species of shells, of which thirteen are recent and four 

 others very closely related to recent forms.^ From the bones 

 of the Scelidotherium, including even the kneecap, being 

 entombed in their proper relative positions,^ and from the 

 osseous armour of the great armadillo-like animal being so well 

 preserved, together with the bones of one of its legs, we may 

 feel assured that these remains were fresh and united by their 

 ligaments, when deposited in the gravel together with the shells. 

 Hence we have good evidence that the above enumerated 

 gigantic quadrupeds, more different from those of the present 

 day than the oldest of the tertiary quadrupeds of Europe, lived 

 whilst the sea was peopled with most of its present inhabitants ; 

 and we have confirmed that remarkable law so often insisted 

 on by Mr. Lyell, namely, that the " longevity of the species in 



' Since this was written, M. Alcide d'Orbigny has examined these shells, and 

 pronounces them all to be recent. 



2 M. Aug. Bravard has described, in a Spanish work (Observaciones Geologuas, 

 1857), this district, and he believes that the bones of the extinct mammals were 

 washed out of the underlying Pampean deposit, and subsequently became embedded 

 with the still existing shells ; but I am not convinced by his remarks. M. Bravard 

 believes that the whole enormous Pampean deposit is a sub-aerial formation, like 

 sand-dunes : this seems to me to be an untenable doctrine. 



