CORALS AND CORAL REEFS — VATJGHAN. 201 



North and south of coral reef areas it seems that the deep-sea 

 corals live in shallower water, because the temperature of the water 

 at and near the surface in higher latitudes is colder than at the sur- 

 face in the Tropics. For instance, some years ago a species of Caryo- 

 phyllia, one of the cup corals, which was collected along the shore in 

 Alaska, was submitted to me by the United States Bureau of Fish- 

 eries. It is an unnamed species, but in its general aspect it resembles 

 the deep-sea forms of the Tropics. There is much scattered evidence 

 of this kind, for example, the corals living on the shores of southern 

 California, but it has never been assembled and systematically pre- 

 sented. There is in the United States National Museum a large 

 amount of material, for which there are records of the depth and 

 temperature of the water and the character of the bottom, that could 

 serve as the basis for such a study. It is my belief that the great gap 

 in present information on coral faunas is the dearth of information 

 on the relations between the deep-sea faunas of the Tropics and the 

 shoal-water faunas of the colder parts of the ocean, both northward 

 and southward from the Tropics. For a long time it has been my de- 

 sire to make a special study of this important problem, and, unless 

 some one else undertakes it, I still hope to be able to give it the atten- 

 tion that, in my opinion, it deserves. 



With regard to the temperature relations of reef-forming corals, it 

 will be said that, except on very shallow flats where the water is 

 stagnant at times and the temperature at such times may range be- 

 tween 33° and 38° C, the upper limit of the temperature endurance 

 of such corals is rarely reached. It is therefore rather to the lower 

 limit of temperature that reef-corals can withstand, that attention 

 should be directed. 



A series of experiments, conducted by A. G. Mayer to ascertain 

 the higher and lower limits of temperature the common corals around 

 the Tortugas can endure, indicate that a lowering of the temperature 

 to 13.9° C. would exterminate the principal Florida reef corals, while 

 the most important inner flat corals would survive. He obtained 

 similar results on the corals around Murray Island, Australia. But, 

 actual reef records show that reef corals do not naturally withstand 

 so much cooling as in the laboratory experiments. 



Temperature records made at lighthouses along the Florida reef, 

 communicated to me by Dr. H. F. Moore of the United States Bu- 

 reau of Fisheries show that vigorous reefs will endure a temperature 

 as low as 18.15° C, the minimum at Carysfort Light between the 

 years 1879 and 1899 ; but at Fowey Eocks, where the minimum drops 

 to 15.6° C, although there are some corals, there is no thriving 

 reef. The species found at the north end of the reef line are those 

 which Mayer's experiments showed capable of withstanding the 

 lowest temperature. The temperature records for the reef line 



