47 ([return])
[ Voyage dans l'Amerique Merid. par M. A. d'Orbigny. Part. Hist. tom. i. p. 664.]
51 ([return])
[ Since this was written, M. Alcide d'Orbingy has examined these shells, and pronounces them all to be recent.]
52 ([return])
[ 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.]
53 ([return])
[ Principles of Geology, vol. iv. p. 40.]
54 ([return])
[ This theory was first developed in the Zoology of the Voyage of the Beagle, and subsequently in Professor Owen's Memoir on Mylodon robustus.]