140 THE WORLD'S LUMBER ROOM. 



building in Paris, that that city, as well as many towns and 

 villages in the vicinity, may be said to be in great part built 

 of them. They are also very numerous in the chalk which 

 extends from Paris to Tours, a distance of fifty miles. One 

 species alone has formed enormous beds in Russia, while 

 the stone of the Great Pyramid is composed chiefly of others 

 called Nummulites,* which are the most highly organised of 

 all the foraminifera, and are the giants of the race, being of 

 about the size and shape of a shilling (Fig. 29). 



One band of nummulitic limestone, often 1,800 miles 

 broad and in many parts of enormous thickness, extends 

 along the Mediterranean and through Western Asia to the 

 North of India and China. 



But though occurring in large quantities in most lime- 

 stone, foraminifera do not usually form so large a propor- 

 tion of it as they do of chalk, which may well be called 

 " foraminiferal limestone." f 



A slice of ordinary limestone, ground so thin as to be 

 transparent, when examined by the microscope, shows that 

 it is made up of all sorts of minute fragments bits of shell, 

 seaweed-skeletons, and coral, with perhaps a few perfect 

 microscopic shells as well. It bears, in fact, a strong resem- 

 blance to the coral-reef rock, which contains on the whole but 

 few perfect remains, owing to the. vigorous way in which it is 

 pounded into sand by the waves, though large mollusks, and 

 even the huge Tridacna, do sink or burrow their way into it 

 and are preserved. 



* Latin, nnmmulus, a small piece of money. 



f Shells of foraminifera may often be found in the sand which comes from 

 a new piece of sponge. 



