Fig. 2 and 7. Skin of the lump-sucker 352 Fig. 3, 4, 5. Thrips physapus 350 XIX. Fig. 1-4. Feet of the monoculus apus 354 Fig. 5 and 6. Skin of the sole fish.--Fig. 7, 8. Scale of the haddock.--Fig. 9, 10. Scale of West Indian perch.--Fig. 11, 12. Scale of sole fish 356 XX. Fig. 1 and A. Cimex striatus, 352.--Fig. 2 and B. Chrysomela asparagi 353 Fig. 3 and C. Meloe monoceros 354 XXI. Fig. 1-24. Various hydræ and vorticellæ 364 XXII. Fig. 26-40. Ditto 392 XXIII. A. Fig. 1-13. Various hydræ, 365. B. Fig. 14-29. Ditto 382 XXIV. A. Fig. 1-10. and B. Fig. 11-24. Ditto 376 XXV. Fig. 1-68. A variety of animalcula infusoria 431 XXVI. Fig. 1-23. Ditto 548 XXVII. Fig. 1-66. Ditto 519 XXVIII. Fig. 1, 2. Transverse section of chenopodium 599 Fig. 3, 4. Transverse section of a reed from Portugal ibid. XXIX. Fig. 1, 2. Transverse section of althæa frutex ibid. Fig. 3, 4. Transverse section of hazel ibid. Fig. 5, 6. Transverse section branch of lime tree ibid. XXX. Fig. 1, 2. Transverse section of sugarcane. ibid. Fig. 3, 4. Transverse section of bamboo cane ibid. Fig. 5, 6. Transverse section of common cane ibid. XXXI. Fig. 1, 2. Crystals of nitre 606 Fig. 3, 4. Distilled verdigrise ibid. XXXII. Fig. 1. Microscopical crystals of salt of wormwood 607 Fig. 2. Microscopical crystals of salt of amber ibid. Fig. 3. Microscopical crystals of salt of hartshorn ibid. Fig. 4. Microscopical crystals of salt of sal ammoniac ibid. N. B. The reader will find no references to the several letters which appear in the bodies of these figures, for reasons assigned by the author as above; in order not to deface the plate, they were suffered to remain. ESSAYS ON THE MICROSCOPE. CHAP. I. A CONCISE HISTORY OF THE INVENTION AND IMPROVEMENTS WHICH HAVE BEEN MADE UPON THE INSTRUMENT CALLED A MICROSCOPE.