CORALS AND CORAL REEFS — VAUGHAN. 211 



fitting the head of the stake, was used for driving the stakes below 

 water level. The disk was made fast by an iron pin through a hole 

 in the head of the stake. 



In the Tortugas, colonies that were attached to disks with hy- 

 draulic cement were planted (a) off the northwest face of Fort Jef- 

 ferson moat wall; (b) on the reef off Loggerhead Key. Colonies 

 naturally attached were studied at the following places: (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 different 

 places at which corals were planted and those at which observations 

 on naturally attached colonies were made are illustrated by plate 

 16, figures A, B, C, and plate 26, figures A, B. 



Observations and experiments were made in the Bahamas 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. 



The colonies in the Tortugas were measured and photographed 

 once a year; while two years elapsed between the first and second 

 measurements of the colonies in the Bahamas. The measurements 

 and photographic exposures of the colonies attached to disks were 

 made while the colonies were out of the Avater. It was shown on 

 page 205 of this article that corals may live out of the water a much 

 longer time than is needed for such operations. 



The following table gives the size of colonies of Favia fragum 

 according to age (pi. 21). The average annual increment is indi- 

 cated by the number preceded by the + sign below that for the av- 

 erage size. The average most rapid growth is during the first year, 

 after which it declines, but should a specimen not attain an average 

 size during the first year, it may grow rapidly during succeeding 

 years until it catches up to the average. Compare specimens Nos. 1 

 and 6 of the table. 



