But the most remarkable and conspicuous feature in this Medusa is the peduncle, which depends, like the clapper of a bell, from the centre of the roof. This is a somewhat thick, fleshy, cylindrical organ, capable of energetic movements, and particularly of enormous elongation and contraction. Sometimes it is shortened so as to be wholly contained in the concavity of the bell, being more or less curled up at the same time at others it is lengthened and allowed to protrude far beyond the margin, hanging down,—not merely to twice the length of the body," as Professor Forbes says;—this gives a very inadequate idea of its powers, but to five times that length. I carefully measured one which was lying quite still, near the side of the glass, (a vessel with straight sides, so that there was no irregular refraction) by applying an ivory scale to it; the peduncle was twenty lines in length, though the bell was scarcely four. The basal part of this long tongue is abruptly diminished to a mere thread, and though this is not conspicuous when the organ is contracted, it becomes a marked character in the extended condition; in the case I have just mentioned the thread-like neck formed just one-third of the whole length, itself reaching far beyond the margin of the bell.
The motions of the Sarsiæ are more energetic than those of any other Medusa that I am acquainted with. In the unbounded freedom of their native sea, and in the limited dimensions of a glass vase, they are alike sprightly. By rapid pump-like contractions of their umbrella, they dart through the water, and shoot round and round, almost with the force and swiftness of a swimming fish. The summit of the bell always goes
