pointed at not finding the dicksonia mentioned by the above
author, or a single arborescent fern. The basalt and tufa dip to
the north, beyond the ridge separating the two Courais, and continue
to do so all the way to St. Vicente. The compact basalt is
still uppermost, and its depth is considerably greater than at the
water-side ; the lower masses are occasionally in an advanced stage
of decomposition, apparently from the effect of the springs issuing
out of them. From the deflections of the streams of basalt and
deposits of tufa, (principally on account of the hills and valleys
of the primitive island, which have also caused the great variations
in the depth of the basalt, and of the existence of which we shall
find positive evidence at St. Vicente,) the dip, though generally
rapid, frequently varies, and consequently we form the best idea
of its great inclination towards the sea, by recollecting, that the
same beds of columnar basalt and red tufa, which are not 100 feet
above the water, close to the beach, are found at a height of 4500
feet in the interior, and that at an horizontal distance of only 7f
geographical miles, or 46,843 feet from the sea, which gives an angle
of 6° 17'. As you approach St. Vicente, you discover dikes descending
through the tufa, and the basalt which composes them
is full of crystals of basaltic hornblende, and occasionally of pyroxene
: I must own, however, that I could not have distinguished
the latter, either by its lustre or conchoidal fracture. The descent
each frond rises, on a slender black stem, and sometimes to a considerable height*
The A. hirsutum resembles a fern found by Olivier in Candiâ, and not yet named. I
have, therefore? given mine the above appellation) from thé thick short-hair at the
back of the fronds. The two following species I believe to be quite new.
Genus Lomaria ?—Frondibus linearibus, semicylindricis, uni-nervatis. Fructifi-
catione totum frondis discum tegente. Tegumine intrà dehiscente. Sp. L .. semicy-
lindrica. B. Genus Aspidium.—Fronde simplice, foliis obliquis oblongis. Fructif. in
lineis brevibus, marginem foliarum tectente, folliculis anello elastico circumdatis. Sp.
Asp. lobaium, B. I have recognised, this fern in Vaillant’s herbier, but it was not named.
to St. Vicente, though scarcely two miles, is more fatiguing than
the whole journey, being very Steep, and covered with blocks of
basalt. The high range on the left is full of basaltic dikes, projecting
like buttresses from the tufa, and mantled with evergreens;
they have evidently descended from the Poul, and are frequently
in such an advanced stage of decomposition, as to be sectile,
acquiring an orange yellow colour; The first village is miserable,
and is about 3J miles from the sea. I turned to the eastward,
towards the towering basaltic rocks which appeared there, and
after walking about two- miles through vineyards, and gardens of
orange trees, and crossing two torrents, the one by a tottering
bridge, I ascended for about half an hour by a rugged winding path,
and found a similar limestone to that which I have before described,
beneath the basalt at Lisbon. Generally speaking, however, it is
of a whiter colour, more crystalline in its texture, contains very
little imbedded siliceous matter, and scarcely any compact masses*
yet from analogy, and from the great depth of the bed, (being
nearly 700 feet from its junction with the superincumbent, basalt,
to my last glimpse of it in the bed of the torrent, nearly level with
the sea,) without a single alternation, I have no doubt of its
being transition, rather than primitive limestone; its more crystalline
texture is probably owing to its vicinity to the basalt. The
drift line of the junction is horizontal, and the limestone has
evidently been deposited regularly and tranquilly, without the
smallest trace of disturbance or confusion. Continuing about a
furlong to the northward, and descending a water-course, (about a
mile in a direct line from the beach,) I found dikes of decomposing
basalt intersecting the limestone, which, from their form
and direction, I should say had evidently descended from above,
and, instead of filling up from below, had flowed into the gaps
created in the limestone by the convulsions which rent the orill
2