In the class _Vermes_ are several species found in various animals inhabiting the northern seas. The sea-snail, _Clio helicina_, is an animal covered with a delicately beautiful sheet, similar to that of the nautilus. The diameter is from two-eighths to three-eighths of an inch. It is found in great quantities near the coast of Spitzbergen. The _Clio borealis_ occurs in vast numbers in some situations near Spitzbergen, but is not found generally in the Arctic Seas. In swimming, it brings the tips of its fins almost into contact, first oil one side and then on another. I kept several of them alive in a glass of sea-water for about, a month, when they gradually wasted away and died. The cuttle-fish, _Sepia_, were found by me in large numbers in the stomachs of the narwals. More than six or seven kinds of _Medusæ_ may be distinguished, among which may be named, _Medusa pileus_, and the purse-shaped, bottle-shaped, and orange-coloured _medusæ_. _Medusa pileus_ is one of the most curious of the tribe. It consists of eight lobes, with a beautiful, irridescent, finny fringe on the external edge of each. A canal, four-fifths the length of the animal, penetrates the centre of it, and two red cirrhi, which may be extended to the length of nearly a foot, proceed from a crooked cavity in opposite sides. The animal is semi-transparent, the colour white, and the finny fringes of deeper red. It is found of various sizes. The substance of the purse-shaped medusa is tougher than that of any other species which I have examined. It has one large open cavity, and is divided by the finny fringes into eight segments, each alternate pair of which are similar. The colour is a pale crimson, with waved purple lines, and the finny fringes deeper crimson. The animal appeared to be almost without sensation. The only evidence it gave of feeling was in an increased vibration of the finny fringes. Though it was cut into pieces, each portion on which there was any of the fringe continued, by its incessant play, to give evidence of life during two or three days, after which it became putrescent, and began to waste away. I have only seen one specimen of this and of the orange-coloured medusa. The colour of the latter was a brilliant orange, and it was not transparent. It was not tenacious of life, having died, to appearance, soon after it was taken.