102 SOMETHING ABOUT I'OLYPES. 



bases on submarine craters; but Darwin, in his admirable account of them in 

 his "Naturalist's Voyage/' asserts that the reef-building corals cannot live at 

 a greater depth than twenty or thirty fathoms; and that mountains and 

 islands which have been submerged by the ocean form rather the bases on 

 which ^^the coral-insects build their radiate cells." Not only have these little 

 animals been employed in changing the sea into dry land since the world was 

 formed, but with them the mighty work of creation began, as is traced "in 

 the great masses of mountain limestone, which have from ages past been ex- 

 posed to all the changes and circumstances of time and chance." 



"Omnipotenoe wrought in them, with them, by them; 

 Hence what Omnipotence alone could do 

 Worms did. ***** 



Frail were then- frames, ephemeral their lives, 

 Their masonry imperishable." 



Thus much for the results of the labours of these Polypes; we will now 

 inquire into their mode of accomplishing their allotted tasks; and of the differ- 

 ences of the several families which are dwellers in the ocean, as contrasted with 

 the little fresh-water Hydra before noticed. 



Those which principally build up the reefs belong to the family of Madrepores 

 and Madrephylls; the former live in scattered cells with laminated walls, on 

 stony, tree-like polyparies, which they form by separating the calcareous matter 

 from the waters of the ocean, reducing it to a solid state. 



^^Throughout the entire series the vital agent will be found to present itself 

 in the form of a soft gelatinous crust, wherewith the exterior of the polypary 

 whatever may be its shape, is closely invested." The Madrephylls differ in the 

 Polypes being scattered over the surface of a laminated solid polypary not tree- 

 like. There are many other families of corals to be noticed, whose inhabitants 

 when living, have, by their varied and gorgeous colours, made the beds of 

 the sea vie in richness and beauty with the gayest parterres. When the eye 

 rests upon them, through the clear transparent water on a calm day, and observes 

 the branched corallines protruding their Polipi of every varied hue — green, blue, 

 violet, and yellow, like trees covered with delicate blossoms, contrasting finely 

 with the huge brain-shaped, flat, or mushroom-like Madrepores, one is ready 

 to exclaim with Ehrenberg, "Where is the paradise of flowers that can rival 

 in variety and beauty these living wonders of the ocean?" 



In the family of Alcyonians, examples of which are abundant on our own 

 shores, the Polypes dwell together in great numbers, studding the surface of 

 an adherent, fleshy polypary, which is divided into two parts; the lower part 

 is a firm substance, whilst the upper is very delicate, and divided into branches, 

 at the end of which are seen the little Polypes spreading their eight pinnated 

 arms, like exquisite flowers. The nutrition imbibed by one is shared by its 

 neighbour, and each in this community contributes to the support of the whole. 

 Another family we may call Corah proper, or Cortical Polypes, as they have 

 been named by some authors; these differ from the Alcyonians in making for 



