EFFECT OF POLYPES ON MINERAL STRATA. 335 , 



appears to have prevailed from the first commencement of 

 Hfe in the most ancient seas, throughout that long series of 

 ages w^hose duration is attested by the varied succession of 

 animal and vegetable exuviae, which are buried in the strata 

 of the earth. In all these strata the calcareous habitations 

 of such minute and apparently unimportant creatures as 

 Polypes, have formed large and permanent additions to the 

 solid materials of the globe, and afford a striking example 

 of the influence of animal life upon the mineral condition of 

 the earth.* 



If there be one thing more surprising than another in the 

 investigation of natural phenomena, it is perhaps the infinite 

 extent and vast importance of things apparently little and 

 insignificant. When v^^e descry an insect, smaller than a 

 mite, moving with agility across the paper on which we 

 write, we feel as incapable of forming any distinct concep- 

 tion of the minutiae of the muscular fibres, which effect these 

 movements, and of the still smaller vessels by which they 

 are nourished, as we are of fully apprehending the magni- 



ftshes, and also small Crustacea, witli which he fed several individuals at 

 Torquay, seizing them with their tentacula, and digesting them within the 

 central sac which forms their stomach. 



* Among the Corals of the Transition Series arc many existing genera, 

 and Mr. De la Beche has justly remarked (Manual of Geology, p. 454) that* 

 wherever there is an accumulation of Polypifcrs such as would justify the 

 appellation of coral banks or reefs, the genera Astrea and Caryophyllia are 

 present ; genera which arc among architects of coral reefs in the present 

 seas. 



A large part of the Limestone called Coral Rng, which forms the elevated 

 plains of Bullington and Cunmer, and the hills of Wytham, on three sides of 

 the valley of Oxford, is filled with continuous beds and ledges of petrified 

 corals of many species, still retaining tlie position in which they grow at the 

 bottom of an ancient sea; as <;oral banks, are now forming in the intertropi- 

 cal regions of the present ocean. 



The same fossil coralline strata extend through the calcareous hills of the 

 N. W. of Berkshire, and N. of Wilts ; and again recur in equal or still greater 

 force in Yorkshire, in the lofty summits on the W. and S. W. of Scar- 

 borough. 



