I believe a small
tribe in Banda Oriental must be excepted; but they are
widely separated from the Pampas Indians, and border close
on those tribes that inhabit the forest, and live on foot. It
appears, therefore, that these arrow-heads are antiquarian [22]
relics of the Indians, before the great change in habits
consequent on the introduction of the horse into South
America.
[1] Since this was written, M. Alcide d'Orbingy has examined
these shells, and pronounces them all to be recent.
[2] M. Aug. Bravard has described, in a Spanish work
('Observaciones Geologicas,' 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.
[3] Principles of Geology, vol. iv. p. 40.
[4] This theory was first developed in the Zoology of the
Voyage of the Beagle, and subsequently in Professor Owen's
Memoir on Mylodon robustus.
[5] I mean this to exclude the total amount which may have been
successively produced and consumed during a given period.
[6] Travels in the Interior of South Africa, vol.
