Last autumn the occurrence of a small Siphonophore in the produce of the surface tow-nets attracted my attention. I first noticed it in the contents of a small net, worked five miles south of the Eddystone, on September 12th, and afterwards it was obtained in great abundance close to the. Plymouth Breakwater, and even inside the Sound. It was brought in numbers to the Laboratory almost every day up to about the middle of October, but after the end of that month it was not seen again.