vaughan: growth-rate of shoal-water corals 593 



That corals have been tremendously over-evaluated is estab- 

 lished. In this connection, reference may be made to Murray 

 and Renard's^ description of their coral sand and coral mud and 

 to some analyses Quin^ has made of the calcareous sand on the 

 shores of St. Croix Island, Danish West Indies. 



From the table on page 596 it will be seen that there is no single 

 formula for the growth-rate of corals, as the rate of growth is 

 different for different species, and in each species it varies in 

 accord with differences in local ecologic conditions. In order to 

 understand the factors controlling growth-rate, the ecologic 

 factors common to the entire reef- tract should be ascertained, 

 and each species should be studied to discover the subordinate 

 ecologic conditions of its more restricted habitat. Investi- 

 gations of the Florida reef-tract along both these lines have been 

 made, and some of the results have been presented in my pre- 

 vious papers. 



Observations and experiments were conducted on the growth- 

 rate of Tortugas corals as follows : 



(1) Colonies obtained from planulae whose history was known. 

 They were planted (a) off the northwest face of Fort Jefferson 

 moat-wall and (b) on the reef off the northwest side of Logger- 

 head Key. 



(2) Colonies cemented to tiles. These were planted (a) off 

 the northwest face of Fort Jefferson moat-wall and (b) on the 

 reef off Loggerhead Key. 



(3) Colonies naturally attached: (a) in Fort Jefferson moat; (b) 

 on piers of the Fort Jefferson wharf; (c) on the outside of the 

 northwest face of the Jefferson moat-wall; (d) on the reef off the 

 northwest face of Loggerhead Key. 



The observations and experiments in the Bahamas were made 

 on the leeward side of the north end of a small island, known as 

 Golding Cay, which is on the east side of Andros Island at the 

 mouth of South Bight. The specimens included, (a) those 

 cemented to tiles and planted, (b) those living naturally attached. 



2 Challenger Repts., Deep-sea deposits, p. 246. 1891. 

 ^ Quin, John T. The building of an island, p. 15. 1907. 



