Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.3)

April, 1836. coral-eating fish. 553 ing property is not new, though it has scarcely been suf- ficiently remarked on. M. Qaoy* mentions it, and I have heard of stinging corals in the West Indies. In the East Indian sea a stinging sea-weed also is found. There was another and quite distinct kind of coral, M^hich was remarkable from the change of colour, which it under- went shortly after death ; when alive it was of a honey- yellow, but some hours after being taken out of water, it became as black as ink. I may just mention, as partly con- nected with the above subjects, that there are here two species of fish, of the genus Sparus, which exclusively feed on coral. Both are coloured of a splendid bluish-green, one living invariably in the lagoon, and the other amongst the outer breakers. Mr. Liesk assured us that he had repeatedly seen whole shoals grazing with their strong bony jaws on the tops of the coral branches.! I opened the in- testines of several, and found them distended with a yellowish calcareous matter. These fish, together with the lithopha- gous shells and nereidous animals, which perforate every block of dead coral, must be very efiicient agents in pro- ducing the finest kind of mud, and this, when derived from such materials, appears to be the same with chalk. April 12th. — In the morning, we stood out of the La- goon. I am glad we have visited these islands : such forma- tions surely rank high amongst the wonderful objects of this world. It is not a wonder, which at first strikes the eye of the body, but rather, after reflection, the eye of reason. We feel surprised, when travellers relate accounts of the vast extent of certain ancient ruins ; but how utterly insignificant are the greatest of these, when compared to the pile of stone here accumulated by the work of various minute animals. Throughout the whole group of islands, every single atom, J * Freycinet's Voyage, vol. i., p. 597. t It has sometimes been thought {vide Quoy in Freycinet's Voyage), that coral-eating fish were poisonous ; such certainly was not the case with these Spari. I I exclude, of course the soil which has been brought here in vessels