Fig. 21 is a scale from the common spring-tail (_Podúra plúmbea_), a little creature which is found plentifully in cellars and other damp places, skipping about with great activity. Some flour scattered on a piece of paper is a sure trap for these little beings. Fig. 3 is one of the scales taken from the back of the celebrated diamond beetle, showing the cause of the magnificent gem-like aspect of that insect. We have in England many beetles of the same family--the weevils--which, although much smaller, are quite as splendid when exhibited under a microscope by reflected light. The wing-case or “elytron” of a little green weevil, very common in the hedges, may be seen on Plate XII. Fig. 10. The reader will observe that all these scales are furnished with little root-like appendages, by means of which they are affixed to the insect. Fig. 13 shows a portion of the wing of the azure blue butterfly, from which nearly all the scales have been removed, for the purpose of exhibiting the pits or depressions in which they had formerly been fastened, and one or two of the scales are left still adherent to their places. The scales are arranged in equal rows like the slates of a housetop, as may be seen on Fig. 18, which represents part of the same wing, to show the scales overlapping each other, and the elegant form which they take near the edges of the wing, so as to form a delicate fringe. The long hair-like down which covers the legs and bodies of the moths and butterflies (which are called Lepidóptera, or scale-winged insects, in consequence of this peculiarity), is seen under the microscope to be composed of scales very much elongated, as is shown in Fig. 17, a portion taken from the leg of a tiger moth. * * * * * The eggs of insects are all very beautiful, and three of the most curious forms are given on Plate VIII. Fig. 2 is the empty egg of the gad-fly, as it appears when fastened to a hair of the horse. Fig. 5 represents the pretty ribbed egg of the common tortoise-shell butterfly; and Fig. 7 is the very beautiful egg of the very horrid bed-bug, worthy of notice on account of the curious lid with which its extremity is closed, by means of which the young larva creeps out as soon as it is hatched. The feathers of birds, and the fur of animals, will furnish many examples of the eggs of parasites, some of which are of extreme beauty. The feather or hair may be mounted in a cell without disturbing the eggs, which should, however, be heated sufficiently to kill the embryo if present.