(Quebrada Onda, on the road to Casa Blanca), at the distance of several
miles from the coast, I noticed a considerable bed, composed exclusively of
Mesodesma donaciforme, Desh., lying on a bed of muddy sand: this shell now
lives associated together in great numbers, on tidal-flats on the coast of
Chile.

VALPARAISO.

During two successive years I carefully examined, part of the time in
company with Mr. Alison, into all the facts connected with the recent
elevation of this neighbourhood. In very many parts a beach of broken
shells, about fourteen or fifteen feet above high-water mark, may be
observed; and at this level the coast-rocks, where precipitous, are
corroded in a band. At one spot, Mr. Alison, by removing some birds' dung,
found at this same level barnacles adhering to the rocks. For several miles
southward of the bay, almost every flat little headland, between the
heights of 60 and 230 feet (measured by the barometer), is smoothly coated
by a thick mass of comminuted shells, of the same species, and apparently
in the same proportional numbers with those existing in the adjoining sea.
The Concholepas is much the most abundant, and the best preserved shell;
but I extracted perfectly preserved specimens of the Fissurella biradiata,
a Trochus and Balanus (both well-known, but according to Mr. Sowerby yet
unnamed) and parts of the Mytilus Chiloensis. Most of these shells, as well
as an encrusting Nullipora, partially retain their colour; but they are
brittle, and often stained red from the underlying brecciated mass of
primary rocks; some are packed together, either in black or reddish moulds;
some lie loose on the bare rocky surfaces. The total number of these shells
is immense; they are less numerous, though still far from rare, up a height
of 1,000 feet above the sea. On the summit of a hill, measured 557 feet,
there was a small horizontal band of comminuted shells, of which MANY