As he did so, the lowering of his head threw his horny ruff far forward, exposing the folds of naked hide on the back of his neck. The silent man-creature on the branch above was quick to note the opportunity. He was displeased at the monster's triumph. He was also interested to see if he had any power to hurt so colossal and well protected a foe. Swinging down by his legs and one hand, he thrust the thorned branch of acacia deep in under the ruff. The monster, jerking his head up sharply at this unexpected assault, drove the long thorns well home. In an instant he was beside himself with rage and pain. Roaring till the blue-and-crimson bird on the tree-top flew off in a panic, he shook his head desperately, and then almost tried to stand upon it. He started to roll over on his back, hoping thus to dislodge the galling thing beneath the carapace, but thought better of it at the first added pressure. His contortions were so vehement that the man discreetly drew himself up to a higher branch, a slow grin widening his heavy mouth, as he marked his power to inflict injury on even such an adversary as the King Dinosaur. The experiment had been successful beyond his utmost anticipations. Like Nature herself, he was continually experimenting, but by no means always with satisfactory results. Suddenly the monster made off, with head held as low as possible, for the edge of the lagoon. Ploughing his way in with a huge splashing, he disappeared beneath the water. A minute later he returned to the surface and swam rapidly towards the jungle on the opposite shore, probably intending to find some projecting stump of a dead limb on which he could scratch the torment from under his ruff. At the edge of the jungle he was joined by another monster, like himself, but smaller--probably one of his mates--and together they disappeared, with heavy crashings, in the rank tangle of the swamp-growths. The man-creature descended from his refuge, carrying in one hand a heavy fragment of branch, which he held awkwardly, as if not over-familiar with the idea of an artificial weapon. He seemed to be groping his way towards some use of it, either as a club or as a stabbing instrument. During the fight, while he was experimenting with the thorn branch, he had evidently had this weapon lodged in some safe crotch. And now he kept handling it with a curious interest.