24 ANNUAL ADDRESS, MDCCCLXXI. 



Their death and decomposition produce a submarine de- 

 posit or bank of vast dimensions, consisting mainly of 

 their silicious shields intermixed with infusoria and mine- 

 ral matter. Its position is from the 76th and 78th de- 

 gree of south latitude, and it occupies an area 400 miles 

 long by 120 wide." 



As an example of an ancient deposit take the state- 

 ment of Dr. Bailey, of New York, of the existence of a 

 white layer of a porcelain clay, allied to the polishing 

 powder known as tripoli, 500 feet in thickness, composed 

 almost entirely of the remnants of these minute beings. 

 This is an example of a deposit of extraordinary thick- 

 ness, but many strata of similar composition reach from 

 thirty to fifty and seventy feet. 



Hurrying on to the other class of microscopic shells re- 

 markable for rearing deposits of magnitude in the earth's 

 crust, namely, to the foraminifera, I will just mention 

 that the limestone formations generally, and especially the 

 late chalk deposits, are essentially accumulated masses of 

 foraminiferous shells. 



The same activity and energy of the extremely little in 

 building up what is colossal, is exhibited at the present 

 day also by these same calcareous-shelled organisms. Dr. 

 Carpenter's dredgings, particularly those in the Atlantic 

 Ocean, have shown the bed of the ocean to be formed of 

 a thick deposit of such shells. The mud he calls "globi- 

 gerina mud," because of the great abundance in it of the 

 particular genus globigerina, and he regards the accumu- 

 lation as equivalent to the formation of a stratum of 

 chalk extending over a large part of the Atlantic sea 

 bed. 



