On examining into the state of our dry provisions it was mortifying to find that the rats and cockroaches had destroyed an incredible quantity, particularly of our biscuit and flour. In one of the casks of the latter more than two-thirds of its contents was deficient. The biscuit was completely drilled through and the greater part would not have been thought fit to eat if we had possessed any of a better quality; I still however hoped to have a sufficiency on board to complete the survey of the north-west coast before our return to Port Jackson, which I now found would of necessity be at least four or five weeks before the time I had fixed upon when we left the Mauritius. As it would take up a great portion of the time we had now left to make a more extensive examination of Shark's Bay than what the French have already performed, and would entirely prevent my going upon the north-west coast again; it was determined that we should not delay here, but pass on and resume our examination of the coast at Cape Cuvier, the northern head of the bay. The only part of Shark's Bay that seems to be at all interesting, and to require further examination, is the eastern side of the bay immediately opposite to the Islands of Dorre and Bernier; but from the very intricate and shoal nature of its approach it is very doubtful whether even a sight of the land in that direction could be procured. The rocks of Dirk Hartog's Island are of a very remarkable formation, consisting of a congeries of quartzose sand, united in small circular kernels by a calcareous cement in which some shells were found embedded. The geological character of this rock is more fully treated upon in the Appendix by my friend Dr. Fitton.