The sound of the motor horn aroused Irene from the thoughtful trance in which, sad-faced and childish, this time, pathetically, she was walking. She had been silent and melancholy ever since, yesterday morning, they had left Rome; Lord Hovenden had stayed behind with Mr. Falx. The long-drawn hooting of the electric horn seemed to remind her of something. She looked down towards the sea-board plain. A cloud of white dust was advancing along the Maremman road from the direction of Civita Vecchia. It hung, opaque, over half a mile of road, fading slowly to transparency towards the tail. At the head, where the dust was thickest, a small black object moved like a rapidly crawling insect across the map-like expanse of plain, drawing the cloud after it. From the opposite direction came another black-headed comet of dust. Like two white serpents they approached one another, as though rushing to battle. Nearer, nearer they came. Irene stopped still to look at them. She was filled with a horrible apprehension. It seemed impossible that they should not crash together. Nearer, nearer. The heads of the two serpents seemed almost to be touching one another. Suppose, just suppose that one of the cars was his.... Inevitably they must collide. Crash and smash—oh, the horror of it! Irene shut her eyes. A few seconds later she opened them. The two white snakes had merged together into one very thick opaque snake. It was impossible to see the little black heads at all. For one horrible moment she thought that they must have destroyed one another. But they reappeared after a little, receding now one from the other, no more approaching. The two serpents were still one serpent, but two-headed, a long amphisbaena. Then, gradually, the middle of the amphisbaena began to grow thin, to fade; a little clump of trees showed through it, dimly at first, mistily, then clearly. The amphisbaena had fallen in half and the two white snakes crawled on, one northwards, the other towards the south, and between their fading tails was a wide and ever wider gap. Irene heaved a deep sigh of relief and ran on after the others. It seemed to her that she had been the witness of a catastrophe miraculously averted. She felt much happier than she had felt all day. On a wide road two automobiles had passed one another. That was all.