92 THE STORY OF THE EARTH AND MAN. 



accidental concurrence of a natural and artificial design. 

 Another very common type is that of the conical 

 Zaphrentis, with a deep cut at top to lodge the body 

 of the animal, whose radiating chambers are faithfully 

 represented by it's delicate Iamella3. Perhaps the 

 most delicate of the whole is the Syringopora, with 

 its cylindrical worm-like pipes bound together by 

 transverse processes, and which sometimes can be 

 dissolved out in all its fragile perfection by the action 

 of an acid on a mass of Corniferous limestone filled 

 with these corals in a silicified state. 



These Devonian corals, like those of the Silurian, 

 belong to the great extinct groups of Tabulate and 

 Rugose corals ; groups which present, on the one hand, 

 points of resemblance to the ordinary coral animals of 

 the modern seas, and, on the other, to those somewhat 

 exceptional corals, the Millepores, which are produced 

 by another kind of polyp, the Hydroids. Some of 

 them obviously combine properties belonging to both, 

 as, for example, the radiating partitions with the 

 arrangement of the parts in multiples of four, the 

 horizontal floors, and the external solid wall ; and this 

 fact countenances the conclusion that in these old 

 corals we have a group of high and complex organiz- 

 ation, combining properties now divided between two 

 great groups of animals, neither of them probably, 

 either in their stony skeletons or the soft parts of the 

 animal, of as high organization as their Paleozoic 

 predecessors. This sort of disintegration of compo- 

 site types, or dissolution of old partnerships, seems 



