The turtles lay their eggs by night--crawling in vast crowds to the central and highest part of the praia--and are occupied till dawn in the operation. They excavate with their broad-webbed paws deep holes in the fine sand. The first which arrives makes a pit about three feet deep, and lays its eggs--about one hundred in number--covering them with sand. The next makes its deposit at the top of the former; and so on till every pit is full. They are so careful in covering up the eggs, that, when they quit the spot, the only marks distinguishable are those which they make when returning to the water--as they go round and round the nest several times in succession to obliterate all traces. The sand, however, remains so loose, that it gives way under foot, and thus the Indian easily discovers the spot. A body of turtles occupy several days in the operation; one party succeeding the other, night after night, till all have deposited their eggs. As the season advances, however, those who have arrived late, in their hurry to lay, appear to take fewer precautions. So powerful is the effect of the sun on these sand-banks, that a few days only are required to hatch the young turtles. It has been so arranged by the Creator, that they always come forth at night, as the heat of the sun would kill them, and they would be devoured by birds of prey and other animals on the watch to seize the dainty morsels. Although the hole from which they emerge may be half a mile or more from the river, instinct teaches them to go in a direct line to the water. A number, however, are caught by their enemies; while enormous quantities of eggs are taken,--both to be used as food, and for the sake of the oil they contain. A curious sight is witnessed from the top of the sentinel's stage at daybreak. The sand appears blackened with the multitudes of turtles-- which, after depositing their eggs, are waddling towards the river; and often, where the margin of the praia is steep, tumbling down the declivity into the water. OIL FROM TURTLES' EGGS.