In order that she may be protected during the period of her incubation against weasels, polecats, ichneumons, and all such vermin, a design exhibiting either wonderful instinct or sagacity, is carried into execution by the male.

As soon as his mate has squatted upon her eggs, he goes to work at the masonic art; and using his great horned mandibles, first as a hod, and afterwards as a trowel, he walls up the entrance to the nest--leaving an aperture just large enough to be filled up by the beak of the female.

The material employed by him for this purpose is a kind of agglutinated mud, which he procures from the neighbouring watercourse or quagmire, and somewhat similar to that used by the common house-swallow for constructing _its_ peculiar nest.

When dried, this mud becomes exceedingly hard--bidding defiance to the teeth and claws of all would-be intruders, whether bird or quadruped; and with the horny beak of the old hen projected outward, and quite filling up the aperture, even the slippery tree-snake cannot find room enough to squeeze his body through.

The female, thus free from all fear of being molested, quietly continues her incubation! When Ossaroo had got thus far with his explanation, Caspar interrupted him with a query.
"What!" said he, "sit all the time--for weeks, I suppose--without ever coming out--without taking an airing?
And how does she get her food ?" As Caspar put this question, and before Ossaroo had time to answer, a noise reached their ears which appeared to proceed from the sky above them.