60 VIEWS OF THE MICROSCOPIC WORLD. 



figure 96 : it is 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 

 at Bayonne and of the Pyrenees, consists of beds of crystalline marble, com- 

 posed of nummulites, and the vast limestone range at the head of the Adriatic 

 Gulf, is also constituted of nummulites, 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 pyra- 

 mid 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 num- 

 mulites and microscopic fossil animalcules 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 lime- 

 stone alternating with beds of plaster of Paris, (gypsum) and flinty matter. 

 These vast beds of marl and limestone are full of foraminiferous and infusorial 

 forms, and deposits of great thicknesses have been discovered, which are entirely 

 constituted of nummulites no larger than a grain of millet seed. The limestone 

 from the quarries of Gentilly abound to such an extent with microscopic struc- 

 tures, that a cubic inch is calculated to contain on an average no less than 

 58,000 shells, and the beds thus constituted 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 foramini- 

 ferous 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 organized 

 remains, which have since been changed by volcanic action. 



Vast beds of animalcular remains occur in Patagonia, the extent and arrange- 

 ment of which is thus described by Darwin : " Here along the coast for hun- 

 dreds 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 



