OF CREATION. 33 



been superseded by those of the present day, so these, 

 in all probability, are destined to give way in their 

 turn to new forms of essentially analogous animals, to 

 which, in time to come, the same great office will be 

 assigned, to clothe with fertile limestone future rising 

 continents.* 



The polyps thus collecting calcareous matter in 

 large quantities, and building vast masses of solid lime- 

 stone, secrete their stony skeletons on the outside of 

 their soft bodies. If, however, we suppose the 

 animals supported on a stem, and that, instead of 

 depositing the earthy particles externally, they are 

 placed in regular shape and order in the substance of 

 the polyp itself, and fill up the stem, the cup-shaped 

 body, and the arms or feelers that surround the 

 mouth, there would result an animal of a very diffe- 

 rent kind, not capable of associating with others of its 

 species to form a compact mass, but possessing a 

 separate and distinct existence, and building a kind 

 of stone plant, of which the roots, the trunk, the 

 branches, and the smaller twigs are each made up 

 of a number of separate and detached particles. A 

 skeleton of this kind, however curious it may seem, was 

 possessed by a vast number of distinct species of 

 animals living in the early seas, and such forms were 

 continued through the whole of the first and second 

 epochs, gradually, however, diminishing in number, 

 and at present scarcely presenting an adequate repre- 

 sentative in two or three comparatively small and unim- 

 portant species of what are called Crinoidal animals. 



The very name which is given to these animals is 

 illustrative of their curious structure and the ar- 



* Owen's Lectures on the Invertebrata, p. 93. 



c 5 



