256 B. W. PRIEST ON SPICULES FROM THE OAMARU DEPOSIT. 



I can quite understand to some extent a vegetable organism 

 penetrating a calcareous substance, but I cannot quite grasp the 

 idea of its doing so with a silicious one, which is of such a 

 different nature, excepting that some chemical caustic action is set 

 up. I should be glad if any member could suggest some idea 

 regarding the modus operandi. But whatever the action may be, I 

 can only follow what Professor Duncan says at the end of his 

 paper : — " It is evident that spicules have to obey the inevitable 

 laws of change, death, and dissolution. The spicule which has 

 lived has to decay, and may live again in another form ; and this 

 new one will have by-and-bye to illustrate in its turn the aesthetics 

 of destroying nature — of that environment which develops the 

 grand outlines of the hills as their rocks crumble away, and which 

 condescends to beautify the tiny microcosm as it passes away and 

 plays its little part in the scheme of evolution." 



DESCRIPTION OF PLATE XIX. 



Figs. 1 and 2. — Spicules showing curious formation in the enlarged axial 



cavities. 

 Fig. 3. — Spicule showing cracked appearance. 

 Fig. 4. — Spicule with enlarged axial cavity. 

 Fig. 5. — Spicule with pitted appearance over the surface. 



