of Cape York. The specimens, in Mr.
Brown's collection from this place, consist of coarse-slaty porphyritic
conglomerate, with a base of greenish-grey compact felspar, containing
crystals of reddish felspar and quartz. This rock has some resemblance to
that of Clack Island above-mentioned.

SWEER'S ISLAND, south of Wellesley's group, at the bottom of the Gulf of
Carpentaria. A stalactitic concretion of quartzose sand, and fine gravel,
cemented by reddish carbonate of lime; apparently of the same nature with
the stem-like concretions of King George's Sound: (See hereafter.) In
this specimen the tubular cavity of the stalactite is still open.

The shore, in various parts of this island, was found to consist of red
ferruginous matter (Bog-iron-ore ?) sometimes unmixed, but not
unfrequently mingled with a sandy calcareous stone; and in some places
rounded portions of the ferruginous matter were enveloped in a calcareous
cement.

BENTINCK ISLAND, near Sweer's Island. A granular compound, like sandstone
recomposed from the debris of granite. Brown hematite, enclosing
quartzose sand.

PISONIA ISLAND, on the east of Mornington's Island, is composed of
calcareous breccia and pudding-stone, which consist of a sandy calcareous
cement, including water-worn portions of reddish ferruginous matter, with
fragments of shells.

NORTH ISLAND, one of Sir Edward Pellew's group. Coarse siliceous sand,
concreted by ferruginous matter; which, in some places, is in the state
of brown hematite. Calcareous incrustations, including fragments of
madrepores, and of shells, cemented by splintery carbonate of lime.

CAPE-MARIA ISLAND, in Limmen's Bight, was found by Mr. Brown to be
composed principally of sandstone. The specimens from this place,
however, consist of grey splintery hornstone, with traces of a slaty
structure; and of yellowish-grey flint, approaching to chalcedony; with a
coarse variety of cacholong, containing small nests of quartz crystals.

GROOTE EYLANDT is composed of sandstone, of which two different varieties
occur among the specimens. A quartzose reddish sandstone, of moderately
fine grain; and a coarse reddish compound, consisting almost exclusively
of worn pebbles of quartz, some of which are more than half an inch in
diameter, with a few rounded pebbles of chalcedony. The latter rock is
nearly identical with that of Simms' Island, near Goulburn's Island on
the north coast.

CHASM ISLAND, WINCHELSEA ISLAND, and BURNE