disappearing, and every filament of conferva being carried up into the interior from the little area which The next instant, the foot meanwhile having made a small advance, the proboscis unfolds again, the tongue makes another sweep, and again the whole is withdrawn; and this proceeds with great regularity. I can compare the action to nothing so well as to the manner in which the tongue of an ox licks up the grass of the field, or to the action of a mower cutting down swathe after swathe as he marches along. The latter comparison is more striking for the marks of progress which each operator Though the confervoid plants are swept off by the tongue of the Mollusk, it is not done so cleanly but that a mark is left where they grew; and the peculiar form and structure of the tongue, which I am about to notice, leaves a series of successive curves all along the course which the Mollusk has followed, very closely like those which mark the individual swathes cut by the mower in his course through the field.
The tongue, by which this operation is performed, is exquisitely constructed for its work. It is indeed a wonderful instrument in the complexity of its armature. The appearance and position of the organ would surprise any one who searched for it for the first time, and as it is readily found, and as Periwinkles are no rarities, let me commend it to your examination. The easiest mode of extracting it, supposing that you are looking for it alone, is to slit the thick muzzle between the two tentacles, when the point of a needle will catch and draw out what
