I NOTICE in NATURE for June 1, 1893, page 107, an inquiry by Mr. R. I. Pocock as to the suicidal habits of scorpions. His conclusion is that if scorpions sometimes kill themselves, the verdict must be “accidental suicide, or suicide while of unsound mind.” I have no evidence to offer as to the habits of Californian scorpions, but I have myself witnessed the deliberate suicide of a rattlesnake, and think that a brief account of it may be worth recording. In the summer of 1888 Prof. Keeler saw a large rattlesnake (with seven rattles) crawl under the foundation of the dome of the six-inch equatorial. With the nice manipulation for which he is famous, Dr. Keeler fastened a pair of blacksmith's tongs about the animal's neck, and brought him into the large marble vestibule of the observatory. The snake was furious and was practically uninjured. After every one had seen him it became a question what to do next. It was resolved to put him into a gallon jar of water. Dr. Keeler had the task of getting the very lively animal (which was some three feet long) into the jar, and of letting go with the tongs; while I undertook to put in the stopper of the bottle at an auspicious moment. All this was accomplished very nicely, and the next step was to drown the snake by inverting the jar at intervals. After a little time it became obvious to every one, the snake included, that the animal must soon be drowned. At this moment the snake ceased any attempt to rise to the surface of the water in the jar, and in the most deliberate manner struck its fangs deep into its body. I have no doubt whatever that the blow was intentional, and with suicidal purpose. It was a single deliberate blow. There was no flurry. As far as one could see the animal was of sound and disposing mind and memory. It had been full of fury at first, but latterly had only sought to escape from the water to the air at the top. When this became hopeless the snake ended its own struggles. I had often heard that snakes (and scorpions) put an end to their own lives. Here is an instance which occurred before my eyes. The snake is now preserved in alcohol at the observatory, and the marks of the fangs are plainly to be seen.