vaughan: growth-rate of shoal-water corals 599 



fifteen years." He estimates that branching species of Pontes 

 grow upward at the rate of 1^ inches per year, while the annual 

 upward growth of massive species of Porites is from ^ to f inch 

 per year. Montipora, of the facies of M. digitata, is said to have 

 an upward growth of not less than five inches per year. 



Stanley Gardiner and F. Wood-Jones have made valuable 

 contributions to the knowledge of the growth rate of Indo- 

 Pacific corals. Wood-Jones has summarized the data in a 

 privately published paper entitled, The rate of growth of reef 

 building corals. His observations in Cocos-Keeling Islands 

 corroborate the estimates of Guppy. According to his recom- 

 putation of the data supplied by Gardiner, based on a collection 

 of presumably 3-year old corals from Hulule, North Male Atoll, 

 a general average of the upward growth for branching forms is 

 about 44 mm. per year, while that of massive forms is about 29 

 mm. Gardiner's estimates for the upward growth of massive 

 forms would be as follows: 



Massive ' ' Astreidae' ' 22 mm. per year 



Massive Fungidae 29 mm. per year 



Massive Perforata 20.3 mm. per year 



As it is probable that these corals, especially the massive ones, 

 are more than three years old, I am inclined to the opinion that 

 the estimates for the massive species are too high. Guppy's 

 estimate of the upward growth of massive Porites, 12,7 to 19.05 

 mm. per year, seems better founded, and falls within the range of 

 a number of the measurements on Porites astreoides. However, 

 recent remeasurements by Mayer of some of the corals meas- 

 ured and marked by Saville-Kent indicate an annual increase 

 in diameter of 1.9 inches (48.26 mm.) per year. As in massive 

 corals the increase in height is usually one-half to two-third 

 that in diameter, the increase in height would probably be 

 between 24 and 32 mm. per year, or very nearly the figures given 

 by Gardiner for massive species of corals. 



The data available for the Pacific corals are not so abundant 

 as those for the Atlantic, nor have the records, with few excep- 

 tions, the same degree of precision. However, they are sufficient 

 for some general comparisons. The general growth rate of 



