CH. vi MABINE FAUNA. OF TALISSE SHOBES 135 



the present day there are only two of them left, viz. Tubipora 

 and Heliopora, that can faMy be called reef-buildmg corals. 

 The reef-building Alcyonarians have, in other words, yielded 

 their places in the struggle for existence to the victorious 

 Madrepores and Astrssids. Now, in connection with this 

 history, it is an interesting fact that the only part of the 

 reef where I ever found a Hehopora was a remarkably poor 

 one. Large patches of sand separated the different lumps 

 of feeble Madrepores and other corals, and every sign was 

 present that there the reef was in anything but a flourishing 

 and -^dgorous condition. WTiatever may have been the 

 struggle for existence here, the competition with Zoantha- 

 rians was reduced to a minimum and Heliopora flourished. 



ISot far from the spot where Hehopora is Hving I 

 come across one of the most beautiful corals I have ever 

 seen. It is called Galacea and belongs to the group of 

 the Imperforata (fig. 8, p. 53). The polype cups, or thecse as 

 they are cahed, are raised ^-^ inch above the general sm'- 

 face of the corallum, and contain most beautiful emerald- 

 green polypes united with one another by delicate fleshy 

 strands of the same colour. "When I first saw it the 

 polypes were as fully expanded as, I beheve, they are capable 

 of being, and the mass looked like some handsome ornament 

 studded with emeralds of the finest quality. 



This general account of a ramble on the reefs of Talisse 

 is perhaps sufficient to indicate the immense variety of form 

 and colour of hving corals that may be observed in different 

 places, but it would take a separate volume to describe in 

 detail all the different creatures, their marks and colours, 

 their movements and their habits, which are to be found 

 upon a hundred yards of such a coast. I have said nothing 

 about the moUusks of the reef, the handsome white Cyprio, 

 covered by its coal-black mantle, the polished tiger cowry 

 (Cypraa tigrina), bivalves with their beautifully marked 



