230 



CARNEGIE INSTITUTION OF WASHINGTON. 



favorable have ever been realized in any area for a protracted period. These 

 two estimates give a measure of the limits of reef formation under continu- 

 ously favorable conditions for upward growth. Such corals as Orbicella annu- 

 laris might form a reef 150 feet thick in between 6,500 and 7,600 years; while 

 such corals as Acropora pahnata might form a similar thickness in 1,800 years. 



Growth-^ate of Orbicella annularis. 



Total of the weights of 5 specimens in 1912, 1,886 grams; total increase in weight of the 5 speci- 



1114 

 mens in 2 years, 1,114 grams, or 7^^ = 59.1 per cent. The average annual increase in height of 



these specimens is .5.7 mm. 



1886 

 Groivlh-rate of Acropora palmata. 



Location and date. 



Tangential 

 spread. 



Golding Cay, tile .33: 



May 11, 1912... 



May 10, 1914... 

 Golding Cay, tile 34: 



May 11, 1912... 



May 10. 1914... 

 Golding Cav, tile 35: 



May 11, 1912... 



May 10, 1914... 

 Golding Cay, tile 38: 



May 11, 1912. . . 



May 10, 1914. .. 

 Golding Cay, tile .39: 



May 11, 1912... 



May 10, 1914... 



76 

 136 (+ 60) 



78 

 193 (+115) 



Radial 

 spread. 



Height. 



Weight. 



mm. 

 78 

 237 (+159) 



69 



187 ( + 118) 



65 

 230 (+165) 



42 



86 (+ 44) 



34 

 148 ( + 114) 



mm. 

 Ill 



158 (+47) 



89 

 124 ( +35) 



109 



171 (+02) 



gm. 

 250 

 670 (+420) 



59 

 295 (+236) 



98 

 480 ( +382) 



104 '■ 275 



lis (+14) 437 (+152) 



82 

 178 (+86) 



163 



700 (+537) 



Total of the weights of 5 specimens in 1912, 745 grams; total increase in weight of the same 



1727 

 6 specimens in 2 years, 1.727 grams, or — — r =231.8 per cent. Average annual increase in height 



of these specimens 24.4 mm. 



A few references to previous literature will indicate the rate of growth of 

 Pacific and Indian Ocean corals. 



H. B. Guppy^ has furnished interesting data on the rate of growth of corals 

 around Keeling Atoll, including in his account the results of some experiments 



'Scottish Geograph. Mag., vol. 5, 1889, pp. 573-576. 



