chip. xi. of Recent Origin, 355 



the only evidence within the limits of the true Pampas 

 which is at all trustworthy is afforded by the still living 

 Azara labiata being embedded in tosca-rock near 

 Buenos Ayres. At Punta Alta, however, we have seen 

 that several of the extinct mammifers, most character- 

 istic of the Pampean formation, co-existed with twenty 

 species of Mollusca, a barnacle and two corals., all still 

 living on this same coast ; — for when we remember 

 that the shells have a more ancient appearance than 

 the bones ; that many of the bones, though embedded 

 in a coarse conglomerate, are perfectly preserved ; that 

 almost all the parts of the skeleton of the Scelidothe- 

 rium, even to the knee-cap, were lying in their proper 

 relative positions ; and that a large piece of the fragile 

 dermal armour of a Dasypoid quadruped, connected 

 with some of the bones of the foot, had been entombed 

 in a condition allowing the two sides to be doubled 

 together, it must assuredly be admitted that these 

 mammiferous remains were embedded in a fresh state, 

 and therefore that the living animals co-existed with 

 the co-embedded shells. Moreover, the Macrauchenia 

 Patachonica (of which, according to Professor Owen, 

 remains also occur in the Pampas of Buenos Ayres, and 

 at Punta Alta) has been shown by satisfactory evidence 

 of another kind to have lived on the plains of Pata- 

 gonia long after the period when the adjoining sea was 

 first tenanted by its present commonest molluscous 

 animals. We must, therefore, conclude that the Pam- 

 pean formation belongs, in the ordinary geological 

 sense of the word, to the Eecent Period. 1 



At St. Fe Bajada, the Pampean estuary formation, 

 with its mammiferous remains, conformably overlies 



1 M. d'Orbigny believes ('Voyage, Part. Geolog.' p. 81) that this 

 formation, though 'tres voisine de la rjotre, est neanmoins de beau- 

 coup anterieure a notre creation.' 



