SOME ANIMAL ARCHITECTS. 145 



these plateaus existed at a uniform depth, so as to afford 

 the necessary basis for the operations of the polypes. That 

 physical geography affords not the slightest justification or 

 foundation for such a belief, is a fact known to every school- 

 boy ; and now that we are tolerably familiar with the nature 

 of the bed of more than one great ocean through recent 

 sounding and dredging expeditions, this theory might be 

 simply relegated to the limbo of impossible beliefs on the 

 ground of its entire inconsistence with plain fact. 



But its improbability might also be argued from the fact of 

 its assuming the existence, in the coral areas of the ocean, of 

 sunken- land, which could not except on the most arbitrary 

 of suppositions be supposed to be limited to these areas 

 alone. And as ridges of land within 150 feet of the surface 

 are unknown in other seas and areas, the theorist would have 

 to explain the singularity of submarine plateaus existing so 

 plentifully in one region and their entire absence in another. 

 Geological science, if appealed to in this matter, would own 

 that it knew of no support which could be given to the 

 assumption of local elevations in the sea-bed; whilst it 

 would suggest that the levelling tendency of the waters of 

 the sea in smoothing down the ocean-bed would weigh 

 greatly against the theorist's views. Thus, if the existence 

 of submarine ridges be disproved, this first theory must 

 necessarily fall to pieces and be wholly put out of court. 

 The suggestion that atolls exist on a volcanic foundation 

 meets with a similar fate when tested by the facts of geology 

 and the logic of common sense. It may thus be remarked, 

 that the mere shape and configuration of many of the atolls 

 is entirely inconsistent with this explanation, no .volcanic 

 crater possessing, for instance, the form of , Bow Atoll, 

 " which is five times as long as it is broad." And the mere 

 question of size is at once seen to prove the utterly un- 

 tenable nature of the suggestion of the origin of atolls. 

 Since it might be asked if reason could support a theory 

 which on its own showing must postulate the existence of a 

 volcanic crater eighty-eight miles long by twenty miles broad 



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