Seeing several water-birds on the fringe of ,the lake, I thought the swirl on the surface was caused by .one of their young. I hurried along the shore, hoping to intercept it and see exactly what it was, but when it came on I saw that it was not a bird but a snake, holding its head above the surface like the spout of a teapot. It saw me when it was ten yards from the shore and changed direction. I followed cautiously, and noted that it was a grass snake, green in colour and with a clean white band on its neck. Choosing a boulder as its landing-place, it swam sinuously in to the side and disappeared. I moved the boulder, and it launched itself again, holding its head up for a moment and then diving. The water was clear, and I was able to watch it swim beneath the surface. It went deeper and deeper, progressing with its tail lower than its head, but managing to gain depth by a swaying motion. In a few seconds it was down out of sight. I watched and waited, but it did not reappear, and I con- cluded that, like most reptiles, a snake can manage well below water. The lake was as calm as glass, and had it showed up anywhere within fifty yards its rising would have disturbed the surface. The habit of swimming on the surface seems to be mainly to enable the snake to see where it is going.