If now the third maxilliped (Fig. 3) be examined, it will be found that, like the swimmeret, it consists essentially of two branches springing from a stalk of two segments. The exopodite, however, is much smaller than the endopodite, and it ends in a flexible lash made up of many small segments. The endopodite forms the main part of the limb, and has five segments, so that, with the two segments of the protopodite, there are _seven_ segments in the main axis of the limb; the second and third segments are partly soldered together, but the line of union can be plainly seen. Attached to the outer side of the first segment is a membranous plate, known as the _epipodite_, on which is inserted, near its base, a brush-like structure, which is one of the gills. In the natural position the epipodite and its gill lie in the gill chamber, hidden from view by the side-flap of the carapace. [Illustration: FIG. 4--WALKING LEGS OF LOBSTER A, Of first pair; B, of third pair] The legs (Fig. 4) can, without difficulty, be seen to consist each of seven segments like those of the maxillipeds, but there is no exopodite. In the young Lobster, when just hatched from the egg, however, each of the legs has a large exopodite like that of the third maxilliped. These exopodites, which are used in swimming, are afterwards lost as the animal grows; but their presence in the young is interesting as confirming the conclusion that the legs, like the maxillipeds, are built on the same plan as the swimmerets. The large claws, and also the first and second pairs of walking legs, end in pincers, or _chelæ_, the penultimate segment projecting in a thumb-like process against which the last segment works. Each leg, except those of the last pair, has on its first segment an exopodite with a gill like those of the maxilliped. [Illustration: FIG. 5--APPENDAGES OF LOBSTER IN FRONT OF THIRD MAXILLIPED A, Eye-stalk; B, antennule; C, antenna (the flagellum is cut short); D, mandible; E, maxillula; F, maxilla; G, first maxilliped; H, second maxilliped. _en_, Endopodite; _ep_, epipodite; _ex_, exopodite; _gn_, gnathobases, or jaw-plates; _p_, palp of mandible; _sc_, scaphognathite] Following the series of appendages forwards from the third maxilliped (Fig. 5), it is easy to trace the gradual reduction of the endopodite and exopodite; while the two segments of the protopodite become flattened and broadened inwards to form the jaw-plates. The mandibles (Fig. 5, D), which are the chief organs of mastication, consist mainly of the much enlarged basal segment of the protopodite, with a strongly toothed inner edge, where it works against its fellow of the opposite side; and the rest of the limb is reduced to a small sensory "palp," which represents the second segment of the protopodite and the endopodite.