This change of dress ("_moulting_," it is sometimes called) is repeated thrice at least in the creature's life, but more generally five or six times. Not only does the outer husk come off at these times, but, wonderful to relate! the lining membrane of all the digestive passages, and of the larger breathing tubes, is cast off and renewed also. After each moult, the caterpillar makes up for his loss of time by eating more voraciously even than before, in many instances breaking his fast by making a meal of his "old clo'"--an odd taste, first evinced, as we have seen, in earliest infancy, when he swallowed his cradle. On Plate I. are shown the chief varieties of form taken by the caterpillars of our British butterflies, and a glance at these will give, better than verbal descriptions, a general idea of their characteristics. Their most usual shape is elongated and almost cylindrical, or slightly tapering at one or both ends. Of these, some are smooth, or only studded with short down or hairs; such are the caterpillars of the Swallow-tail butterfly (fig. 1), of the Brimstone (fig. 2), Clouded Yellows, and Garden, and other white butterflies. Others, of the same _general_ form, are beset with long branched spines, making perfect _chevaux-de-frise_; such {10} are those of the Peacock, Red Admiral, Painted Lady, and the Silvery Fritillaries. The caterpillars of another large section have the body considerably thicker in the middle (rolling-pin shaped), and the tail part two-forked, or _bifurcate_. This form belongs to the numerous family that includes the Meadow-brown (fig. 3), the Ringlets, and many others. The _bizarre_ personage, at fig. 4, turns to the graceful White Admiral butterfly. The Purple Emperor begins his royal career in the curious form shown at fig. 5--a shape unique among British butterflies, as beseems that of their sovereign; and he carries a coronet on his brow already. All those beautiful little butterflies called the Hair-streaks (fig. 9), the Blues (fig. 10), and the Coppers, have very short and fat caterpillars, that remind one forcibly of wood-lice--a shape shared also by that small butterfly with a big name, the Duke of Burgundy Fritillary (fig. 8), an insect very distinct from the Fritillaries above mentioned with thorny caterpillars. The _legs of a caterpillar are usually sixteen in number_, and composed of two distinct kinds, viz. of _six true legs_, answering to those of the perfect insect, and placed on the foremost segments of the body; and of _ten_ others, called "_prolegs_;" temporary legs, used principally for strengthening the creature's hold upon leaf or branch.