14 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



tions from the animal. It is to the action of Xullipores and 

 Polyzoa that we owe the great banks of calcrete fringing the 

 shores of Africa, India and Ceylon, and extending over 

 thousands of square miles. The cementation of loose 

 grains into hard rock contemporaneous with their deposi- 

 tion is a matter of great interest, and many geological 

 puzzles can only be solved on this hypothesis. 



In this brief outline of the work done by organisms in 

 the making and unmaking of rocks, I have only been 

 able, in the limits of the address, to touch lightly on many 

 points of great interest which are worthy of fuller treat- 

 ment. In preparing this address I have been more 

 impressed with the vastness of what we do not know than 

 with the little that has been gleaned. 



Our Society offers unique opportunities for the prose- 

 cution of research along these untrodden paths. Let us 

 find the paths and walk in them worthily. 



