"These creatures have a peculiar manner of throwing the head towards the tail, and flouncing the tail towards the head, when they are desirous of removing any object of annoyance; it is at that time these animals seem to recover from their torpidity, and evince the greatest activity in their movements. When much annoyed, they throw the body about with great activity, coiling up the head, tail, fins, &c. in a somewhat rotundiform position, and if the tormenting object is not removed, dash out again in full activity of body, then return to the rotundiform position, and there remain for a short period, apparently exhausted by their efforts; but on the cessation of the irritating cause, the animal quietly resumed its original position, perhaps dropping one or two of its wearied fins, according as its own sensations of ease or comfort might dictate.
"When nothing irritated this tender Mollusk, it would remain tranquilly floating upon the surface of the water, with scarcely any movement but that which proceeded from the undulating motions of the digitated extremities of the fins, as well as an occasional slight twisting action of the same organs.
"I placed some small specimens of Porpita in the glass of water containing the Glauci, to observe if they would attack them. For some time one of the Glauci was close to a Porpita, and was even annoyed by the tentacles of the latter touching its back; yet the Glaucus bore this, although with the usual characters of impatience, yet without attempting to attack it. At last it seized the Porpita between its jaws, and by aid of a powerful lens, an excellent opportunity was afforded me of