Page:Natural History, Mollusca.djvu/127

 closely watching the devouring process, which was effected by an apparently sucking motion; and at this time all the digitated processes of the fins were floating about, as at other times, when the animal was at rest. But I did not observe, in one single instance, that they were of any use to the animals, either to aid in the capture, or to securely hold their prey when in the act of being devoured; for the animal seems to depend merely upon the mouth in capturing its prey, as, in this and other instances which I had opportunities of observing, they seized their prey instantly with the mouth, and held it by that power alone, whilst by a kind of sucking motion the prey was devoured. The digitations may, therefore, only be regarded as appendages to the fins, to aid the animal, perhaps, in the direction of its movements, as it was observed that they turned and twisted them about during the progressive motion—that is, when this tardy animal is pleased to progress,—as if in some way or other to direct the movements of the animal.

"The Glaucus, after eating the tentacles, and nearly the whole of the soft under surface of its prey, left the horny portion, and remained tranquilly reposing upon the surface of the water after its meal, the only motion visible in the animal being the playing of the digits of its fins. The mutilaterl remains of the Porpita sank to the bottom of the glass.

"Soon after, another Glaucus began a devouring attack upon another Porpita which had been placed in the glass, eating a little of it, and then ceasing after a short meal, occasionally renewing the attack at short intervals. On examining the Porpita which had been partially devoured by the ravenous