I38 REPORTS ON INVESTIGATIONS AND PROJECTS. 



Favia fragum. — In 1909 records were begun on six colonies living in the 

 moat. In 1910, two of these were apparently dead, two showed very little 

 or no growth, while the other two had grown considerably. The death of 

 two colonies and the retardation of growth in two others were probably due 

 to exposure at low tide ; and the other two, probably for the same reason, are 

 really not thriving. Evidently this species can not withstand atmospheric 

 exposure so well as species with more porous skeletons. Of the two speci- 

 mens that had grown, one had increased in length over 100 per cent; the 

 other had increased in breadth 57 per cent. Data obtained in 1908* showed 

 that planulae attached between May 11 and May 18 had grown by July 22 to 

 calices having a diameter of 3.5 to 5.5 mm., with an average of about 4.5 mm., 

 or they had attained this size at an age between 66 and 73 days. At this rate 

 of growth, at the end of the first year a specimen should be about 20 mm. in 

 diameter. An adult specimen, about 60 mm. in length, is estimated, from 

 the combined data procured to the present time, to attain its size within about 

 three years. 



In 1910 the number of growth records was increased to 30, nearly all of 

 the specimens being below the level of the lowest tide, and therefore not sub- 

 ject to exposure between tides. 



Mceandra areolata. — Only one growth record is available. It is of a speci- 

 men transferred from the piers of the Fort Jefferson dock to the moat and 

 planted near the southeast exit. Its length in 1908 was 40 mm. ; in 1909, 

 54 mm.; in 1910, 80 mm.; an increase of 100 per cent in two years. Its 

 breadth in 1908 was 27 mm. ; in 1909, 46 mm. ; in 1910, 69 mm. ; an increase 

 of 156 per cent in two years. Its height in 1909 was 28 mm. ; in 1910, 42 

 mm. ; an increase in height of 50 per cent in one year. It is estimated that 

 this specimen is about four years old ; and, as it is almost adult, indicates that 

 the probable age of an adult specimen is from four to five years. 



In 1910 the number of records for M. areolata was increased to 21. 



Mceandra viridis. — The only growth record is of a rather large head living 

 on the reef off Loggerhead Key. Its length in 1909 was 432 mm. ; in 1910, 

 445 mm. ; an increase of 13 mm. or 3 per cent. Its breadth in 1909 was 

 325 mm. ; in 1910, 341 mm. ; an increase of 16 mm. or 5 per cent. Its height 

 in 1909 was 347 mm. ; in 1910, 371 mm. ; an increase of 24 mm. or 7 per cent. 

 In actual amount of growth, the increase in size, compared with that of young 

 Mceandra clivosa colonies, is slight, suggesting that this colony is approaching 

 its growth limit. 



Mceandra clivosa. — Seven colonies, all living in the Fort Jefferson moat, 

 were measured in 1909 ; one of these had disappeared in 1910, leaving 6 colo- 

 nies which were again measured. The percentage increase in length and 

 breadth ranged from 14 per cent to 113 per cent, the 113 per cent represent- 

 ing an increase in length from 99 to 211 mm. The increase in thickness for 

 the six specimens was, respectively, 124 per cent, 15 per cent, 48 per cent. 

 114 per cent, and 76 per cent. 



Although information on the initial stages of this species is not yet suffi- 

 cient, there is some. A young specimen, which is now growing on one of the 

 piers of the Fort Jefferson dock and has diameters of 30 and 40 mm., re- 

 spectively, probably represents a year's growth, as it was not seen when the 

 pier was examined in 1909. A major diameter of 300 or 400 mm. is common 

 for large specimens. From the data obtained, it is estimated that a colony 



* Carnegie Institution of Washington, Year Book No. 7, 1908, p. 135. 



