, r )8 VIEWS OF THE MICROSCOPIC WORLD. 



grain of sand. The spiral shell of the nummulite is delineated in figure 96: it is 

 Fig. 96 separated into a very great number of small cells of nearly equal extent, 

 which communicate with each other by an opening through the partitions 

 of the several chambers. It is supposed that each cell once contained a 

 distinct animal, and that the entire shell formed the common habitation 

 of a vast multitude. The chalk formation atBayonne and of the Pyrenees, 

 consists of beds of crystalline marble, composed of nummulites. and the 

 vast limestone range at the head of the Adriatic Gulf, is also constituted of nummu- 

 lites, having the shape and size of a small pea. At Suggsville, in the United States, 

 is a chain of mountains three hundred feet high, entirely made up of a single species 

 of this fossil. The great pyramid of Egypt, which covers eleven acres of ground, 

 and rises to the height of about 600 feet, is constructed partly of limestone, which 

 consists of nummulites and microscopic fossil structures that form a cement for the 

 larger shells. 



There exists in the north of France an extensive tract of country, one hundred 

 and eighty miles long, and about ninety in breadth, within whose limits Paris is 

 included. This region is termed by geologists the Paris Basin, and the exterior 

 crust of the earth is here composed of layers or strata of sand, marl, and limestone 

 alternating with beds of plaster of Paris (gypsum) and flinty matter. These vast 

 beds of marl and limestone are full of foraminiferous and other forms, and deposits 

 of great thicknesses have been discovered, which are entirely constituted of nummu- 

 lites no larger than a grain of millet seed. The limestone from the quarries of Gen- 

 tilly abound to such an extent with microscopic structures, that a cubic inch is cal- 

 culated to contain on an average no less than 58,000 shells, and the beds thus con- 

 stituted are of great extent and thickness. It is even asserted by geologists as an 

 undoubted fact, that the edifices of the splendid capital of France, as well as of the 

 towns and villages of the neighboring provinces, are almost entirely built of stones 

 composed of the shells of foraminiferous animals; and that these minute fossils are 

 scarcely less numerous in other tertiary formations, extending in the south of France 

 from Champagne to the sea. They likewise abound in the strata of the Gironde, 

 and in those of the basin of Vienna. The invisible, calcareous polythalamia, or 

 many-chambered shells, form, according to Ehrenberg, the compact earth and rocks 

 of Central North America, and constitute immense deposits at the sources of the 

 Mississippi. Even the stupendous chain of the Andes, belonging, as it does, to the 

 chalk formation, is conjectured to have been originally composed of minute organ- 

 ized remains, which have since been changed by volcanic action. 



Vast beds of microscopic forms occur in Patagonia, the extent and arrangement 

 of which is thus described by Darwin : " Here along the coast for hundreds of miles, 

 we have one great tertiary formation, including many tertiary shells, all apparently 

 extinct. The most common shell is a massive, gigantic oyster, sometimes even a 

 foot in diameter. The beds composing this formation are covered by others of a 

 peculiar, soft, white stone, including much gypsum, and resembling chalk, but really 

 of the nature of pumice stone. It is highly remarkable from its being composed, to 

 at least one-tenth of its bulk, of minute fossils, and Prof. Ehrenberg has already rec- 

 ognized in it thirty marine forms. This bed, which extends for five hundred miles 

 along the coast, and probably runs to a considerably greater distance, is more than 



