CONTOUR DIVING 1 43 



tiny in comparison with the big fish, rush from all sides 

 and begin a systematic cleaning of the large fish's head. As 

 in most relationships between different species of animals, 

 this is founded on mutual benefit, the parrotfish getting 

 a free cleaning, and the wrasse finding a supply of parti- 

 cles of food ready at hand (Plate III) . 



On the very last dive of 1930, we were 30 feet down 

 with the bottom at least a hundred feet beneath, when, 

 without the slightest warning, the green water rained 

 blue parrotfish. They were all deep cserulean blue (Scarus 

 ccertdeus) almost unmarked, and they varied from about 

 six inches to four feet. Hundreds and hundreds streamed 

 obliquely past and downward, unending lines of vivid 

 blue, and they extended far beyond my vision in every 

 direction. Some were the merest shadow ghosts of parrot- 

 fish in the distance, others almost brushed the glass, and 

 the downpour did not cease — we merely passed through it. 

 It seemed as if all the parrotfish of Bermuda had suddenly 

 decided to leave for the depths of the open sea (Plate V) . 



Once before, a few miles to the westward, when I de- 

 scended on a particularly rough day in my helmet to a 

 depth of 30 feet I saw a similar migration or gathering 

 of the blue parrotfish clans. On this occasion they were 

 filled with curiosity about me and milled about for five 

 minutes, fairly blanketing me — almost obliterating the 

 surrounding seascape. 



Well out from shore on one of these contour dives I 

 had the thrill of suddenly seeing a thin, endless sea-serpent. 



