How Animals Work. 



down through the depths of those seas of a past geo- 

 logical epoch. When we learn that a single cubic inch 

 of Poorbandar limestone has been computed to contain 

 more than a million Foraminifera, we realize the utter 

 fruitlessness of attempting to give a numerical defini- 

 tion of these vast deposits. 



Nor are the Foraminifera the only microscopic marine 

 organisms which extract from the surrounding sea water 

 the materials for the construction of exquisitely shaped 

 and extremely minute homes. The somewhat closely 

 allied Radiolaria make the most beautifully designed 

 shells or " tests " of silica extracted from the sea, and 

 their remains form an ooze at depths of from two 

 thousand to three thousand fathoms. Like the Fora- 

 minifera, their history can be traced far back in the 

 records of the past, their fossil shells being very plen- 

 tiful in the rocks of Bermuda, Barbados, in Richmond, 

 Virginia, and Sicily. The familiar Tripoli powder used 

 for polishing consists largely of their remains. Their 

 flinty " tests " are most varied and beautiful in shape, 

 while the individual animal, again, is of the simplest 

 character, destitute of any highly specialized limbs or 

 organization, yet capable of extracting minute quantities 

 of silica from the sea and working it up into the most 

 graceful designs. 



