d probably many others
remain yet to be discovered in the north-west, a large space there being
as yet a blank upon the chart. All the islands of the group, with the
exception of the low ones of coral formation to the westward, appear to
be inhabited, but probably nowhere very densely, judging from the
comparatively small number of natives which we saw, and the circumstance
of the patches of cultivation being small and scattered, while the
greater part of the large islands is either covered with dense forest, or
exhibits extensive grassy tracts with lines and clumps of trees. Such of
the islands as were examined consisted of mica slate, the line of
direction of the beds of which is nearly the same as that of the
Archipelago itself, and the physical appearance of the other islands
leads me to believe that the same rock prevails there also.

CORAL REEFS OF THE LOUISIADE ARCHIPELAGO DESCRIBED.

One of the most remarkable features connected with the Louisiade
Archipelago is the manner in which its shores are protected by the coral
reefs which have frequently been alluded to above. The principal of these
are good examples of that kind distinguished by the name of barrier
reefs. Rossel Reef has already been described, and the only other large
one of this description which we saw more than a portion of, is that
partially encircling South-east Island at a variable distance from the
land, then passing to the westward as far as longitude 152 degrees 40
minutes, where it ceases to show itself above water; thence, however, the
edge of a bank of soundings (represented on the chart by a dotted line)
which is suddenly met with in coming from the deep blue unfathomed water
to the southward, can be traced in a continued line to the westward as
far as the Jomard Isles, whence it turns round to the northward for ten
miles further, where our examination ended. This last may be considered
as a submarine extension of the barrier, which probably reappears again
above water, and passing to the northward of the Calvados Group, reaches
as far as the northern entrance to Coral Haven, enclosing nearly all the
high islands of the Archipelago. The expanse of water inside when not
occupied by land usually exhibits a depth of from 15 to 30 fathoms, with
numerous sunken patches of coral, and several reefs which partially dry
at low-water. The shores of the islands also are generally protected by
fringing coral reefs, the largest of which is that extend