THEIR NUMERICAL IMPORTANCE. 41 



and yet how insignificant the sum, when we regard, 

 in the same point of view, the enormous mass consti- 

 tuting the sea-coasts of the earth ! The researches of 

 D'Orbigny relative to these microscopic organisms go 

 to prove that the remains of Foraminifera constitute, 

 in a great measure, banks, which by their accumula- 

 tion interrupt the progress of the navigator, stop up 

 bays and straits of the sea, fill up harbours, and, to- 

 gether with various corals, produce those islands that 

 rise up in the warm regions of the Pacific Ocean. 



But more than this, the almost invisible shells 

 we are now contemplating have had to do with the 

 construction of the surface of the earth, and it is easy 

 to adduce facts to show that they contribute much 

 to the formation of vast geological deposits. Take, 

 for example, as a striking case, the environs of Paris. 

 The calcaire grassier of that extensive basin is in 

 certain places so filled with Foraminifera, that a cubic 

 inch from the quarries of Gentilly contains something 

 like 58,000 of their shells, and that in beds of great 

 thickness and of vast extent. This gives an average 

 of about 3,000,000,000 for the cubic yard, a number 

 so great as to put a stop to all further calculation. 

 Now, as all Paris, and the towns and villages of the 

 neighbouring departments are built of stone quarried 

 from this deposit, it is evident that, without exagge- 

 ration, the capital of France, and all the neighbouring 

 towns, are constructed principally of the shells of 

 Foraminifera. 



Again, the remains of the Foraminifera are not less 

 abundant in the tertiary formations extending from 

 Champagne to the sea, as also in the basins of the 



