Fig. 11, in the centre of the Plate, shows one of the most curious examples of insect structure, the proboscis or trunk of the common bluebottle-fly. The maxillary palpi covered with bristles are seen projecting at each side, and upon the centre are three lancet-like appendages, two small and one large, which are used for perforating various substances on which the insect feeds. The great double disc at the end is composed of the lower lip greatly developed, and is filled with a most complex arrangement of sucking-tubes, in order to enable it to fulfil its proper functions. The numerous tubes which radiate towards the circumference are strengthened by a vast number of partial rings of strong filamentary substance, like that which we have already seen in the breathing-tube of the silkworm. Some of these partial rings are seen on Fig. 12, a little above. The mode in which the horny matter composing the rings is arranged upon the tubes is most wonderful, and requires a tolerably high power to show it. The fine hairs upon the proboscis itself afford most admirable practice for the young microscopist. They should, when properly lighted and focused, be quite black and sharp. Any errors of manipulation will cause them to be “fuzzy.” Fig. 5 shows the tongue of the common cricket, a most elegantly formed organ, having a number of radiating bands covered with zigzag lines, due to the triangular plates of strengthening substance with which they are furnished, instead of the rings. A portion more highly magnified is shown at Fig. 6, exhibiting the manner in which the branches are arranged. * * * * * The legs of insects now claim our attention. Fig. 9, Plate VII., shows the “pro-leg” of a caterpillar. The pro-legs are situated on the hinder parts of the caterpillar, and, being set in pairs, take a wonderfully firm hold of a branch or twig by pressure toward each other. Around the pro-legs are arranged a series of sharp hooks, set with their points inwards, for greater power in holding. Fig. 10 represents one of the hooks more magnified.