FIG. 1. Boat-fly, leg 2. Gadfly, empty egg 3. Diamond Beetle, scale 4. Scale, Fritillary, Adippe 5. Egg, Tortoiseshell Butterfly 6. Head and Eyes, Zebra Spider 7. Eyes, Bed-Bug 8. Scale, Death’s-Head Moth 9. Sting, Wasp 10. Scale, battledore, Azure blue 11. Do. ordinary scale 12. Eye, Harvest Spider 13. Wing Membrane, Azure Blue 14. Scale, Anthocera cardaminis 15. Do. Peacock Butterfly 16. Do. Tiger Moth 17. Do. Thigh of Tiger Moth 18. Wing and Scales, Azure Blue 19. Scale, Lepisma 20. Saws, Sawfly 21. Scale, Podura 22. Hair, Black Human 23. Do. Human Beard 24. Do. do. aged 25. Do. Humble Bee 26. Do. Tiger Moth, Larva 27. Do. Dormouse 28. Do. Rat 29. Do. do. long hair 30. Do. Sheep 31. Do. Mole 32. Do. Rabbit 33. Scale, Greenbone Pike 34. Hair, Red Deer 35. Do. fine, Sea Mouse 36. Do. do. large 37. Do. do. Badger 38. Do. do. long-eared Bat 39. Fibre, Linen 40. Do. Cotton 41. Do. Silk 42. Scale, Perch 43. Do. do. [Illustration: VIII.] The scales of some of the fishes are shown on Plate VIII., in order to exhibit their mode of growth by successive layers. The scales are always enveloped in membranous sacs, and in some cases, as in the eel, they do not project beyond the surface, and require some little observation to detect them. A scale of an eel is shown on Plate XI. Fig. 14, and is a magnificent object under polarised light. Fig. 33 is a scale of the greenbone pike; and Figs. 42 and 43 are scales of the perch, showing the roots by which they are held in their places. The roach, dace, bleak, and many other similar fish have a beautiful silvery substance on the under surface of the scales, which was greatly used in the manufacture of artificial pearls, glass beads being thinly coated in the interior with the glittering substance, and then filled in with wax. A piece of sole-skin, when preserved in Canada balsam and placed under the microscope, is a very beautiful object. More examples of hairs, and other processes from the skin, together with the structure of the skin itself, of bone, of blood, and the mode in which it circulates, are given on Plate X.