"Moreover, it is a fact now well known and well established that the coralligenous polyps, namely, this great family of animals with coral stocks, such as the millepores, the madrepores, astrææ, meandrinæ, etc., prepare on a great scale at the bottom of the sea, by a continual secretion of their bodies, and as the result of their enormous multiplication and their accumulated generations, the greatest part of the calcareous matter which exists. The numerous coral stocks which these animals produce, and whose bulk and numbers perpetually increase, form in certain places islands of considerable extent, fill up extensive bays, gulfs, and roadsteads; in a word, close harbors, and entirely change the condition of coasts. "These enormous banks of madrepores and millepores, heaped upon each other, covered and intermingled with serpulæ, different kinds of oysters, patellæ, barnacles, and other shells fixed by their base, form irregular mountains of an almost limitless extent. "But when, after the lapse of considerable time, the sea has left the places where these immense deposits are laid down, then the slow but combined alteration that these great masses undergo, left uncovered and exposed to the incessant action of the air, light, and a variable humidity, changes them gradually into fossils and destroys their membranous or gelatinous part, which is the readiest to decompose. This alteration, which the enormous masses of the corals in question continued to undergo, caused their structure to gradually disappear, and their great porosity unceasingly diminished the parts of these stony masses by displacing and again bringing together the molecules composing them, so that, undergoing a new aggregation, these calcareous molecules obtained a number of points of contact, and constituted harder and more compact masses. It finally results that instead of the original masses of madrepores and millepores there occurs only masses of a compact calcareous rock, which modern mineralogists have improperly called _primitive limestone_, because, seeing in it no traces of shells or corals, they have mistaken these stony masses for deposits of a matter primitively existing in nature."