One more character inscribed on the pebble remains to be interpreted; it is the minute branch of coral partially imbedded in the flint.[P] The surface of this coral, when seen with a powerful lens, is found to be studded with small pores or cells. In a recent state, each cell was inhabited by a living polype or animalcule, which, though permanently united at its base to the general mass, had an independent existence, and possessed sensation and voluntary motion; expanding its thread-like feelers or tentacula to catch its prey, and withdrawing, at will, into its little cell.[Q] [P] Plate I. immediately below the shell and spine of Echinus. [Q] For a popular account of recent and fossil corals, see 'Wonders of Geology,' 6th Edit., vol. ii. Lecture VI. p. 589. [Illustration: Lign. 16:--A Coral-polype preserved in flint: magnified 500 diameters.] From these investigations, we learn that the Pebble, which has formed the subject of our contemplation, had its origin in a living zoophyte that was growing on a rock, in a sea whose boundaries have long since been swept away; that corals, shells, and echini inhabited the bottom of the deep; and that fishes related to existing families, sported in the waters of that ancient ocean. In fine, we have presented to us the scene so exquisitely described by the American poet:-- [Sidenote: THE CORAL GROVE.] THE CORAL GROVE. Deep in the waves is a coral grove. Where the purple mullet and gold fish rove, Where the sea-flower spreads its leaves of blue, That never are wet with the falling dew. But in bright and changeful beauty shine, Far down in the green and glassy brine. The floor is of sand, like the mountain drift. And the pearl-shells spangle the flinty snow; From coral rocks the sea-plants lift Their boughs, where the tides and billows flow; The water is calm and still below. For the winds and the waves are absent there, And the sands are bright as the stars that glow In the motionless fields of upper air: There with its waving blade of green, The sea-flag waves through the silent water, And the crimson leaf of the dulse is seen. To blush like a banner bathed in slaughter. There with a light and easy motion The fan-coral sweeps through the clear deep sea; And the yellow and scarlet tufts of ocean, Are bending like corn on the upland lea; And life in rare and beautiful forms, Is sporting amidst those bowers of stone. Percival. [Illustration: Lign. 17:--Minute Corals from the Chalk;[R] _highly magnified_.] [R] Note IX. _Minute corals from the Chalk._ [Sidenote: MICROSCOPIC CORALS.]