Corals, Sea-anemones, and Jelly-fishes 



761 



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

 immediately s n-inks back upon its base, ejecting all the water with which its expanded tissues 

 were fil ed and revealing the presence of the hard radiating coral beneath. Each of the calcareous 

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

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

 iNew 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 huo-e 



[il'll/ord-on-Sea. 



BLEACHED CORALS FKOM THE GREAT BARRIER REEF. 



EranchiDg stag;'s boin corals are chiefly represented in this group. Several of the large solitary mnshroom-coraia may, however, be observed 



in the foreground, 



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 Braix- 

 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 Stau's-iiorn Corals, with their innumerable allies 

 and variations, are j)roduced. The colours of the coral-polyps are as brilliant and diverse 

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



9() 



