the timidity induced by its novel circumstances, such as the increased light, the slight depth of water, the heightened temperature, &c., it was interesting to watch its proceedings, especially at night, with a candle; as then it was more active. I had put it into a vase of water with two inches of fine siliceous sand for a bottom, on which the tube lay along. After a few tentative essays, it grew bold enough to thrust out its cork-like head, projecting the combs as it did so, so as to shew more of their bases. They thus separated from each other, and each assumed the form of a concave fan, or of a turkey's tail were the shafts of the feathers stripped of the vanes.
Their use was now apparent. The animal is a burrower in sand; I repeatedly lost it during my absence from the room, and found it plunged to the very bottom. Its mode of burrowing is as follows. If the animal is not lying rightly, it turns on its axis within the tube (which it can do with perfect facility, as there is no organic connexion between its body and its dwelling, as there is between a Mollusk and its shell), until the third of the circle inclosed by the angle of the combs is next the surface. These organs are now thrust outwards and downwards, so that their points enter the soil like shovels; then by muscular movements of the head they are lifted upwards and backwards, carrying in their concavity their load of sand, which they throw over the upper margin of the tube, behind the head. The combs, or, as I may now call them, digging-forks, immediately make another plunge, and deliver their spadeful of sand in like manner. A considerable hollow is presently formed,
