324 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



The highest temperature is 35.0° C. on June 14, 1912, the next highest 

 34.4 C. on June 22. The lowest temperature is 18.6 C. on February 17, 

 1913; and the next lowest is 18.9 C. on December 28, 1912, thus giving 

 an extreme range of 16.4 C. The greatest weekly range is 8.3 C. between 

 June 21 to 28, 1912, also July 19 to 26, 1912, and the least 2.0 C. between 

 August 9 to 16. 



The following appear to be the average and the extreme temperatures 



for each month: 



Monthly average and range in temperature at Tortugas. 



There were three well-marked northers, but they did not produce a 

 weekly range of more than 6.7 C. above the lowest in the norther. 



The daily water-temperature records for Fort Jefferson were made by 

 Mr. George C. Short, mate, U. S. N., in accordance with an agreement 

 entered into with Dr. Mayer. 



The temperature records for means of ten-day periods along the Florida 

 reef tracts were furnished by Dr. H. F. Moore, of the U. S. Bureau of Fisheries. 



The salinity and temperature records near Bermuda, the Bahamas, and 

 Florida were compiled by Mr. W. W. Welsh, naturalist of the U. S. Coast 

 and Geodetic Survey steamer Bache, Capt. C. C.Yates commanding, and the 

 copy was supplied by the U. S. Bureau of Fisheries through Dr. H. F. Moore. 



I heartily thank all who have so generously assisted in assembling the data. 



Except the last mentioned, all the records were in the Fahrenheit scale 

 and have been converted into centigrade by Miss R. L. MacGregor. After 

 conversion all figures were checked by two persons acting jointly. 



DAILY WATER-TEMPERATURE RECORD AT FORT JEFFERSON, 

 TORTUGAS, FROM JUNE 16, 1911, TO JUNE 16, 1912. 



In addition to the data contained in the table on pages 326-330, the 

 following statement by Dr. Mayer is here pertinent: 



"The tides on July 22-23 ( tn e spring tide came on July 21) were very low and 

 the water in the moat was, I am told, 32.8 C. and 33. 3 C. Your corals were 

 exposed in this heat in an almost flat calm. The air temperature was 34.7 C. 

 and 35.0 C. respectively on the two days. A great many Siderastrea radians 

 seem to have been killed in the exposed parts. 



"The temperature of tide pools in shallow places on the reef ranged from 

 33.0 C. to 38.0 C. at 2 p. m. on July 23, at nearly low (or about low) water; and 

 a great many Diadema, large numbers of Octopus, Fissurella, various mollusca and 

 small fishes were killed." 



