WINDOW-PANE OYSTER INVESTIGATIONS. 135 



the majority feeing quite normal and healthy-looking. As 

 was to be expected, no Placuna larvae were discovered in the 

 plankton. The gonads of most of the oysters were large and 

 swollen, but of a sickly grayish-yellow colour instead of the 

 rich orange of the normal ripe gonad. A microscope examina- 

 tion failed to reveal either ova or spermatozoa, although 

 numerous gonads were examined. 



On the 16th, 17th, 18th, and 19th inspection work was 

 rendered impossible owing to the continuously heavy rain. 

 On the 20th Nachchikuda Bay was inspected. There is a 

 small bed of oysters at the head of this bay which do not grow 

 so rapidly as those in other parts of the lake, but they appear 

 to be much hardier. None of these oysters were dead. 



On the 21st the south-west corner of the lake was inspected. 

 All the oysters were dead and putrefying, and occasionally 

 one saw the bodies of oysters floating on the surface in a high 

 state of decomposition. 



On the 22nd the inspection was completed by a line of dives 

 taken from 600 yards south of Periya Kalmunai to the mouth 

 of the Polokarai-ar ; but no oysters were found except at 

 the last station, where the oysters were abundant but all dead. 



Whenever possible, tow-nettings were taken throughout the 

 inspection, but no Placuna larvae were discovered. The usual 

 planktonic organisms were not present, and mosquito larvae 

 and small water beetles formed the only captures. 



A further inspection was commenced on May 19. The 

 Government canoe was kindly placed at my disposal by Mr. T. 

 A. Hodson, the Assistant Government Agent at Trincomalee, 

 and I was assisted by a peon using one of the local boats. 

 Dives were made at 110 stations. In his Report on the 

 Window-Pane Oyster Investigations, 1912, Dr. Pearson divided 

 the oyster-bearing portions of the lake into twenty -two areas, 

 which are lettered from A to W, and I have retained these areas 

 in the present report. A description of the conditions 

 regarding the oysters in each area in May, 1913, follows. 



Wherever possible, ten oysters were measured at each 

 station. 



Area A. — Second-year oysters were found in the northern 

 extremity of Nachchikuda Bay. They averaged 4-627 X 



