[_And drop a pearl_. l. 84. Many are the opinions both of antient and modern concerning the production of pearls. Mr. Reaumur thinks they are formed like the hard concretions in many land animals as stones of the bladder, gallstones, and bezoar, and hence concludes them to be a disease of the fish, but there seems to be a stricter analogy between these and the calcareous productions found in crab-fish called crab's eyes, which are formed near the stomach of the animal, and constitute a reservoir of calcareous matter against the renovation of the shell, at which time they are re-dissolved and deposited for that purpose. As the internal part of the shell of the pearl oyster or muscle consists of mother-pearl which is a similar material to the pearl and as the animal has annually occasion to enlarge his shell there is reason to suspect the loose pearls are similar reservoirs of the pearly matter for that purpose.] 85 3. "YOUR myriad trains o'er stagnant ocean's tow, Harness'd with gossamer, the loitering prow; Or with fine films, suspended o'er the deep, Of oil effusive lull the waves to sleep. You stay the flying bark, conceal'd beneath, 90 Where living rocks of worm-built coral breathe; Meet fell TEREDO, as he mines the keel With beaked head, and break his lips of steel; Turn the broad helm, the fluttering canvas urge From MAELSTROME'S fierce innavigable surge. 95 --'Mid the lorn isles of Norway's stormy main, As sweeps o'er many a league his eddying train, Vast watery walls in rapid circles spin, And deep-ingulph'd the Demon dwells within; Springs o'er the fear-froze crew with Harpy-claws, 100 Down his deep den the whirling vessel draws; Churns with his bloody mouth the dread repast, The booming waters murmuring o'er the mast. [_Or with fine films_. l. 87. See additional notes, No. XXIX.] [_Where living rocks_. l. 90. The immense and dangerous rocks built by the swarms of coral infects which rise almost perpendicularly in the southern ocean like walls are described in Cook's voyages, a point of one of these rocks broke off and stuck in the hole which it had made in the bottom of one of his ships, which would otherwise have perished by the admission of water. The numerous lime-stone rocks which consist of a congeries of the cells of these animals and which constitute a great part of the solid earth shew their prodigious multiplication in all ages of the world. Specimens of these rocks are to be seen in the Lime-works at Linsel near Newport in Shropshire, in Coal-brook Dale, and in many parts of the Peak of Derbyshire. The insect has been well described by M. Peyssonnel, Ellis, and others. Phil. Trans. Vol. XLVII. L. LII. and LVII.] [_Meet fell Teredo_. l. 91. See additional notes, No. XXX.] [_Turn the broad helm_. l 93. See additional notes, No. XXXI.]