. The
eucalyptus pulv., a species of eucalyptus having a glaucus-coloured
leaf, of dwarfish habits and growing mostly in scrub, betrayed the
sandstone formation, wherever it existed, This was the case in many
parts of the County of Cumberland, in some parts of Wombat Brush, at
the two passes on the great south road, over a great extent of country
to the N.W. of Yass Plains, and at Blackheath on the summit of the Blue
Mountains. On the other hand, those open grassy and park-like tracts,
of which so much has been said, characterise the secondary ranges of
granite and porphyry. The trees most usual on these tracts, were the
box, an unnamed species of eucalyptus, and the grass chiefly of that
kind, called the oat or forest grass, which grows in tufts at
considerable distances from each other, and which generally affords
good pasturage. On the richer grounds the angophora lanceolata, and the
eucalyptus mammifera more frequently point out the quality of the soil
on which they grow. The first are abundant on the alluvial flats of the
Nepean, the Hawkesbury and the Hunter; the latter on the limestone
formation of Wellington Valley and in the better portions of Argyle;
whilst the cupressus calytris seems to occupy sandy ridges with the
casuarina. It was impossible that these broad features should have
escaped observation: it was naturally inferred from this, that the
trees of New South Wales are gregarious; and in fact they may, in a
great measure, be considered so. The strong line that occasionally
separates different species, and the sudden manner in which several
species are lost at one point, to re-appear at another more distant,
without any visible cause for the break that has taken place, will
furnish a number of interesting facts in the botany of New South Wales.

It was observed both on the Macquarie river and the Morumbidgee, that
the casuarinae ceased at a particular point. On the Macquarie
particularly, these trees which had often excited our admiration from
Wellington Valley downwards, ceased to occupy its banks below the
cataract, nor were they again noticed until we arrived on the banks of
the Castlereagh. The blue-gum trees, again, were never observed to
extend beyond the secondary embankments of the rivers, occupying that
ground alone which was subject to flood and covered with reeds. These
trees waved over the marshes of the Macquarie, but were not observed to
the westward of them for many miles; yet they re-app