h 



580 



FOEMATION OF CORAL REEFS. 



[Ch. XLIX. 



more 



over the stony nucleus."^ 



The growth of those corals which form reefs of solid stone 

 is entirely confined to the warmer regions of the globe^ rarely 

 extending beyond the tropics about two or three degrees, 

 except mider peculiar circumstances, as in the Bermuda 

 Islands, in lat. 32'' N., where the Atlantic is warmer by the 

 Gulf-stream. The Caribbean seas are very coralliferous. 

 The Pacific Ocean, throughout a space comprehended between 

 the thirtieth parallels of latitude on each side of the equator, 

 is extremely productive of coral ; as also are the Arabian and 

 Persian Gulfs. Coral is also abundant in the sea between 



Lscar. Flinders 



Malabar and the island of Madagf 



New Holland 



Fig. 146. 



having a length of nearly 1,000 miles, and as being in one 

 part unbroken for a distance of 350 miles. Some groups of 

 coral islands in the Pacific are from 1,100 to 1,200 miles in 



length, by 300 or 400 in 

 breadth, as the Dangerous 

 Archipelago, for example, and 

 that called Eadack by Kot- 

 zebue ; but the islands within 

 these spaces are always small 



points, and often very thinly 

 sown. 



MM. Duchassaing and Jean 

 Michelotti have lately written 

 a concise account of the dis- 

 tribution of corals in relation 



i-£3-ee<:^vi;^=-A.^^ir,:*.' 



Mceandrina lahyrhWiica, Lain. 

 Syn. Cceloria Jahyrbithka 

 M. Edw. & J. Ilaimes. 



to the depth of the sea.f 



A certain number of zoophytes are littoral and are left 

 uncovered by every low tide — for instance, species of the 



genera 



Zoanthes and PalytJioa. In shallow spots where a 

 certain depth of water always covers the corals, the species 



of ForiteSy Astrcea^ Madre^pora^ Solenastrwa^ and Fhyllangia^ 

 flourish. The Mceandrince are sometimes left uncovered. All 

 these may be termed sub-littoral. At a depth of f 



om 



^^ 



Ehrenberg, Nat. imd Bild. der Coralliaires des Antilles. Mem. della 



Coralleninseln, &c., Berlin, 1834. 

 t Supplement au Memoire sur 



les 



Keale Accad. delle Scienze di Torino, 

 serie ii. torn, xxiii. 



