May 11.—­We travelled four miles to the E.N.E.  The anabranches of the river continued; the ranges of quartz porphyry approached several times close to the river.  Oak trees and drooping Melaleucas grew abundantly in its bed, and along the banks.  Higher up we crossed fine flats with lagoons and lakes covered as usual with Nymphaeas.  We encamped in latitude 18 degrees 32 minutes 37 seconds, after passing a Casuarina creek, with high banks and a sandy bed.  This creek separated the table land from a broken low range of hills, composed of a coarse-grained sandstone.  The banks of the river here seemed to have been swept away; a broad sheet of sand, covered with fine drooping tea trees, was slightly furrowed by a narrow stream of water, which seemed for the greater part filtering through the sands; chains of water-holes at its left side, fringed with Casuarinas, appeared to be anabranches of the river, and to be connected with the main stream during the rainy season.

I have to mention that a species of Sciadophyllum, nearly allied to Sc. lucidum, (Don. iii. p. 390,) was found in the lava scrub of the valley of lagoons:  it was a small tree with large digitate leaves, each of them composed of from eleven to thirteen oblong acuminate, glabrous leaflets, which were about five inches long; and it attracted the attention of my companions as much by its ornamental foliage as its numerous terminal racemes of bright scarlet coloured flowers.

After having celebrated Whit-Sunday with a double allowance of fat cake and sweetened tea, I started with Charley to reconnoitre the country to the westward.  Our friendly stream not only turned to the north, but afterwards to north-east and east-north-east; and though I had not succeeded in leaving it from Reedy Brook—­not having been able to cross the lava streams of the basaltic table land—­I now concluded, from the nature of the pebbles, and sands of the creek which we had crossed last, that the basalts and lavas had ceased, and that a passage to the westward would be practicable.

I followed the Casuarina Creek up to its head, and called it “Big Ant-hill Creek,” in consequence of numerous gigantic strangely buttressed structures of the white ant, which I had never seen of such a form, and of so large a size.

The general course of the creek was north-north-west:  for the first ten miles it was without water, but its middle and upper course was well provided with fine reedy holes, the constant supply of water in which was indicated by Nymphaeas, and other aquatic plants.  At its left side near the junction I observed, as before mentioned, a coarse grained sandstone, and, at less than a mile higher up, I found flint rock; and, wherever I examined afterwards, the rocks proved to be coarse grained granite and pegmatite, the decomposition of which formed a sandy soil on the slopes, and clayey flats along the creek.  The latter, however, were very limited.  The ant-hills were intimately connected