446 KEELING ISLAND. [ HAP. xx. 



of-wjir, many jelly-fish, and the Aplysia or sea-slug of the Capo cle 

 Vcrd Islands, it is stated in the voyage of the Astrolabe, that an 

 Actinia or sea-anemone, as well as a flexible coralline allied to 

 Sertularia, both possess this means of offence or defence. In the 

 East Indian sea, a stinging sea-weed is said to be found. 



Two species of fish, of the genus Scarus, which are common 

 here, 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 intestines of 

 several, and found them distended with yellowish calcareous 

 sandy mud. The slimy disgusting Holuthuria (allied to our 

 star-fish), which the Chinese gourmands are so fond of, also feed 

 largely, as I am informed by Dr. Allan, on corals ; and the bony 

 apparatus within their bodies seems well adapted for this end. 

 These Holuthuriic, the fish, the numerous burrowing shells, and 

 nereidous worms, which perforate every block of dead coral, must 

 be very efficient agents in producing the fine white mud which lies 

 at the bottom and on the shores of the lagoon. A portion, how- 

 ever, of this mud, which when wet strikingly resembled pounded 

 chalk, was found by Professor Ehrenberg to be partly composed 

 of siliceous-shielded infusoria. 



April 12/i. In the morning we stood out of the lagoon on our 

 passage to the Isle of France. I am glad we have visited these 

 islands : such formations surely rank high amongst the wonderful 

 objects of this world. Captain Fitz Koy found no bottom with a 

 line 7200 feet in length, at the distance of only 2200 yards from 

 the shore; hence this island forms a lofty submarine mountain, 

 with sides steeper even than those of the most abrupt volcanic 

 cone. The saucer-shaped summit is nearly ten miles across; and 

 every single atom,* from the least particle to the largest fragment 

 of rock, in this great pile, which however is small compared with 

 very many other lagoon-islands, bears the stamp of having been 

 subjected to organic arrangement. We feel surprise when travel- 

 lers tell us of the vast dimensions of the Pyramids and other great 



* I exclude, of course, some soil which lias been imported here in 

 vessels from Malacca and Java, and likewise some small fragments of 

 pumice, drifted here by the waves, The one block of greenstone, more- 

 over, on the northern island must be excepted. 



