CORALS, SEA-ANEMONES, AND JELLY-FISHES 761 



mistaken for a big sea-anemone allied to the dahlia-anemone. On being disturbed, however, it 

 immediately shrinks back upon its base, ejecting all the water with which its expanded tissues 

 were filled, and revealing the presence of the hard radiating coral beneath. Each of the calcareous 

 radii, which are now clearly defined through the thin semi-transparent skin, corresponds in position 

 with one of the internal membranous partitions, and also with the origin of one of the tentacles. 

 New mushroom-corals are produced as buds thrown off from the parent, which attach themselves 

 and secrete a foot-stalk, to which they remain affixed, like the young of the feather star-fish, for 

 the earlier epoch of their existence. Ultimately, however, they become detached, and, falling 

 from their stalks, lie loosely on the sea-bottom, after the manner of their parents. The huge 



PhM hy U^. SavilU-Kent^ f.Z.X.l 



[UilUrd-m-Sia 



BLEACHED CORALS FROM THE GREAT BARRIER REEF 



Branching stag i-horn corals are chiefly represented in this group. Sefcra! of the large solitary mushroom-corals may, hoive^^er, 



be obserTjeJ in the Joreground 



coral-masses commonly known as MADREPORES, out of which coral-islands and reefs are con- 

 structed, all commence as a single coral-animal, with its contained skeleton analogous to the 

 mushroom-coral, though in all instances much smaller. The buds developed by the coral- 

 polyp in these instances remain attached to the parent. If they spread out laterally, they 

 build up by accumulation the large flattened or sub-spherical masses known as Brain- 

 CORALS and Star-CORALS, which are most abundant on coast-line reefs, or form the bases of 

 the outer barrier-reefs. Where, on the other hand, the budding is terminal or oblique, 

 branching tree-like growths such as the Stag'S-HORN Corals, with their innumerable allies 

 and variations, are produced. The colours of the coral-polyps are as brilliant and diverse 

 as those of ordinary sea-anemones, hving reefs, whereon a number of different species are 



