A still more highly endowed relation spins a similar fabric, upon which are loosely agglutinated numbers of small dead shells, grit, and even opercula a quarter of an inch in diameter. In weight, size, and number of its constituents this exterior armour is altogether disproportionate to the extreme tenuity of its foundation. Too unsubstantial to sustain its own weight, it sprawls, like the track of a tipsy snail, indeterminately, slowly developing its sinuosities over the irregular surface of a rock, and slightly adherent thereto, throughout its whole length. Of this there seem to be several nicely shaded grades, some in the form of galleries laboriously built of a mixture of mud and sand, and each indicating superiority to the naked denizen of the clement mud. They seem to be superior in appearances also, for some of the animals display brightly coloured plume-like tentacles, long and capable of being ostentatiously fluttered. The individual worm next to be described typifies such a wonderful advance that it might almost be designated a subsequent and intrusive sport, no marked are the distinctions it exhibits. It is one of the shell-binders (PECTINARIA), but its mansion of mosaics is unique and beautiful. In the universal struggle for place, self-preservation, and food, the animal has acquired a higher order of intelligence and keener perceptions of safety and of the niceties of life than its fellows. Living in sand and mud, in obedience to some gracious instinct, it gathers numbers of small shells, grit, and fragments of coral wherewith to construct a tube, somewhat similar in shape to the horn of cornucopia, and from three to six inches long. The materials are cemented together in accordance with a symmetrical design, the interior being lined with a transparent substance, which, when dry, is readily separable from the casing! This creature accomplishes by calculation, choice, and dexterity that which a subtle chemical process does unconsciously for the more advanced mollusc, and that it practised the art of the interlocking of atoms ages before the birth of Macadam can scarcely be doubted. My imagination loves to dwell on the perceptive faculties possessed by this lowly creature, a creature soft and delicate, merely such and such a length of gelatinous substance, slightly stiffened and toughened and graced with a pair of tentacles glittering like tinsel extended from a marvellously constructed tube. In certain structural details the animal (which in appearance has greater resemblance to a caterpillar than a worm) is even more remarkable than the ornate dwelling it constructs, for it is an actual though living prototype of the fabled race (catalogued by Othello with the anthropophagi)-- "Whose heads Do grow beneath their shoulders."