that just described ; then a considerable vertical depth with
oblique lines, like lines of cleavage, on its surface; where it
became harder, covering the cliff with a ragged outline of large
indurated flakes, shooting upwards. I made two sketches, the one
when half way down the cliff; the other when on the summit,
with my face turned inland, so as to take in thè thrée peaks,
Plate 1, A, which are composed of the same tuih. intersected by
dikes, which appears between the sandstone and the sea in the
other drawing, Plate 7, B **, thé sandstone having been depositèd
on it, only in thé lower part of the island, which happens to be the
middle. The looser sandstone immediately below thè flaky, and
which yielded to the fingers, contained, in its upper and outer
surface, an àrripullina, (or marine ampullaria) a large helix resembling
thè h. plicata, fig. 17°, but differing, from the plate being on
the last whorl, which does not advance as far into the mouth ; a
still larger, wholly unknown to me, fig. 16, and two others, the
one, a helicella of De Perussac’s groupe, marginata, the other, a
helicigona of the groupe, vorticesd. I found none of these shells,
which were notoriously in a fossil state, deep within the mass,
although it does not follow that they are not to be found there ;
but some òf the upper masses of this loose sandstone on the plain,
seemed almost entirely composed, throughout, of a small bulimm,
fig. 15, two species of helicella, fig. 13 and 14, each belonging to
De Ferussac’s groupe, aplostomee, the one perfectly smooth, and the
other striated longitudinally. All these shells were quite white.
I found no ampullina amongst the shells of the beach, no bulimi
b It is of a greenish-grëy colour, with orange-red ferruginous spots; it becomes
hardér upwards, and its specific gravity is 1.95.
c Since named h. subplicata. Soioerby.—E d .
d In examining the beds of sandstone at the northern extremity of the Punta Araya,
near Cumana, frequently bathed by the sea, Baron de Humboldt observed univalve
shells, resembling the genus helix, mixed with marine bivalves. Voyage, 1. 2, c. 5.