The females among the native tribes have little confidence reposed in them by the opposite sex, from fear that their secret plans and expeditions might be divulged by them: when, therefore, they form a plot to steal or kill cattle, they are careful to conceal their schemes from the weaker sex, and boys associate with them; for in instances not a few, when plans for marauding excursions have been overheard by the females, the latter have betrayed them to the stock-keepers, and thus frustrated their intentions. But may not this proceed from the want of mutual confidence between the parties? Among the tribes a chieftain does not preserve an hereditary rank, chiefs being chosen for superior bravery, being the best hunter, or having a superior mind.[65] Thus men in a state of nature choose their leaders; and we may observe a similar order of things among gregarious animals. CHAPTER IX. Perch, and other fish—An elegant couple—Kangaroo dogs—Black and white cockatoos—Vegetable productions—Mr. O’Brien’s farm—Herds of cattle—Bush life—Proceed towards the Murrumbidgee river—A bush track—Romantic country—Arrive on the banks of the Murrumbidgee—Cross the river—Swamp oaks, and other trees—Remarkable caves—Return to Yas—Superstitious ceremonies—Crystal used in the cure of diseases—Mode of employing it. Large quantities of native perch are caught in the Yas and Murrumbidgee rivers; their flavour is delicious: their average length is nineteen inches, and the weight from three to six pounds: they have however been taken from two and a half to three feet in length, and weighing seventy pounds; and some even of the enormous size of one hundred, and one hundred and twenty pounds:[66] the breadth is great in proportion to the length of the fish. Those I examined were of a yellowish-green colour, covered with irregular black spots, with a silvery abdomen. They are named by the colonists, “river cod;” and by the aborigines, “Mewuruk.”[67] In the stomach of this fish I frequently found shell-fish, of the genus _Unio_, in an entire state. The larger kind of these shells the natives of the Tumat country call “Nargun;” and the smaller, usually found in rivulets or creeks, “Pindaquin, or Bucki.” Occasionally half-digested masses of green caterpillars, and other insects, were also found in the stomach of this fish. In the Tumat country, varieties of the “river cod,” are called by the natives Bewuck, Mungee, &c. Another fish of the family of perches is also caught in the Yas, Murrumbidgee, and other large rivers in the colony: it is called the “perch” by the colonists, and “Kupé” by the natives. I preserved a specimen, caught in the Murrumbidgee, measuring seventeen inches in length, and six inches at its greatest breadth, containing a fine roe: twenty inches was the greatest length they had as yet been taken in this river; but, like the “river cod,” it increases more in breadth, in proportion to its weight, than in length.