Note 20 — V
Reading edition
"Corals and Coral Islands," p. 356, etc.
[21] Aragonite, like ordinary limestone, is calcium carbonate, but its atoms seem to be differently arranged, so as to make it a less stable compound, and it has a different crystalline form. Some calcareous organisms are composed of aragonite, others of ordinary calcite.
[22]"Bulletin Geol. Soc. Belgium," vol. ix. (1895, p. 3). Also notice in Geol. Mag., July, 1895, p. 329.