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to transparency similar to that of horn was observable. These cir- 

 cumstances have also been observed in the madreporites of Gothland, 

 But those which are generally met with in this island are of a dark 

 ash colour, the ridges, however, of these, formed by the transverse 

 plates of the corals give them very much of the appearance which 

 has just been noticed. 



Attributing the formation of these corals to the operations of the 

 madreporean or medusean polype, let us endeavour to trace the little 

 architect through its wonderful labours. Agreeable to the observa- 

 tions of Donati, each of the legs, as he terms them, of the polype 

 are provided with two processes which are applied to each side of one 

 of the perpendicular laminae, whilst a muscular pyriform body,attached 

 to the other end of the leg, gives to it the power of employing that 

 motion which is necessary for the accomplishment of its task. The 

 young polype, disposed on an appropriate spot, may be considered as 

 completing its operations by two distinct processes : the secretion 

 and separation of carbonate of lime from the sea water, conveyed 

 through the pyriform body; and its deposition, at its moment of 

 secretion, by the tsvo small processes, where the economy of the 

 animal directs. Proportioned to the number of legs possessed by the 

 infant animal, was probably the number of perpendicular laminae, or 

 pillars converging to the centre, which it began to erect; these when 

 raised to ^certain height, appearing to have been connected together 

 by an horizontal plate of the same substance. On these the animal 

 erected similar pillars, and placed on these a covering similar to that 

 with which he had completed the first compartment. Thus seems to 

 have proceeded the incessant labours of the minute artist : and as the 

 number of its legs, or instruments, increased, and as they extended in 

 length, so must the number of the perpendicular laminae, and the cir- 

 cumference of the horizontal plates have also augmented. Thus must 

 this curious fabric have derived its fashion from the growth and form 

 gf this minute and wonderful animal. 



