16. Coral-polype in flint. 47 17. Minute Corals from chalk. 50 18. Fossil cases or shields of animalcules from Richmond, Virginia; highly magnified. 53 19. Several species of Lamp-shells (_Terebratulæ_) from the chalk, near Brighton. 63 20. Silicified Oyster from the chalk. 65 21. Coniferous wood in flint, from Lewes Priory. 68 22. Several species of Ammonite. 69 23. The body of a recent microscopic animalcule (_Nonionina_), the shell having been removed by immersion in acid. 81 24. A branch of Sponge in flint; a minute Coral from chalk; and a section of a pebble enclosing a zoophyte (_Siphonia Morrisiana_). 85 25. Flints deriving their shapes from Zoophytes (_Ventriculites_). 89 26. Ventriculites in chalk; from Lewes. 90 27. Portions of three kinds of recent corals. 94 LITHOGRAPHS. Page. Plate I. A rolled flint pebble, having a Choanite as a nucleus, and the remains of an echinus and spine, shell, and coral, apparent on the surface. 5 Plate II. A longitudinal section of the pebble, showing the structure of the enclosed _Choanite_. 42 Plate III. A polished section of an Ammonite, having the septa or chambers filled with variously coloured spar, &c. 70 Plate IV. Polished sections of two pebbles from the Isle of Wight; in the upper specimen, the transition from opaque flint to cloudy chalcedony and transparent quartz crystals, is beautifully shown; the lower specimen is richly tinted; the dark appearance is derived from manganese. 86 [Illustration: _Plate I._ "THE PEBBLE" _Page 5_] THOUGHTS ON A PEBBLE. "Honoured, therefore, be thou, thou small pebble, lying in the lane; and whenever any one looks at thee, may he think of the beautiful and noble world he lives in, and all of which it is capable." Leigh Hunt's _London Journal_, p. 10. PART I. Well might our immortal Shakspeare talk of "_Sermons in stones_;" and Lavater exclaim, that "_Every grain of sand is an immensity_" and the author of 'Contemplations of Nature' remark, that "_there is no picking up a pebble by the brook-side without finding all nature in connexion with it._"