THE WINDOW-PANE OYSTERS. 33 



REPORT ON THE WINDOW PANE OYSTERS (PLACUNA 



PLACENTA, "MUTTUCHCHIPPI") IN THE BACK 



WATERS OF THE EASTERN PROVINCE 



(JUNE, 1907). 



By Arthur Willey, F.R.S. 

 With Plate and Text-Figures, 



Introduction. 



nj^'^HE first systematic biological survey of the Tamblegam pearl 

 J- fishery grounds in recent years was carried out by Mr. James 

 Hornell in 1905, and an account of it was published in Part II. of 

 the Ceylon Marine Biological Reports (June, 1906).* There was no 

 inspection of the beds in 1906. 



On June 5, 1907, exactly at the break of the south-west monsoon, I 

 proceeded to Trincomalee to examine and report upon the occurrence 

 of window-pane oysters in the estuaries and backwaters lying to the 

 south of Koddiyar Bay. At this time a strong wind was blowing 

 almost incessantly day and night, rendering the harbour and great 

 bay as well as lake Tamblegam, which lies in the midst of a flat 

 plain, very choppy. Shortly after my arrival the Assistant Govern- 

 ment Agent at Trincomalee, Mr. C. S. Vaughan, C.C.S.,t informed 

 me that the open season for pearling in the Tamblegam lake had 

 terminated on May 15, according to the terms of the lease schedule, 

 and that it now became necessary to make a fresh inspection of the 

 Tamblegam pearl fishery grounds ; accordingly I added this work 

 to my programme. 



By the terms of the new lease of the Tamblegam placuna fishery, 

 which commenced on January 1, 1907, window-pane oysters may 

 not be collected during a close season extending from the middle of 

 May to the end of the year, and during the open season, from Janu- 

 ary 1 to May 15, they may not be collected of a less size than 5h 

 inches in shortest diameter. As the close season is not known to 

 coincide with the spawning season, it will be seen that these restric- 

 tions as to season and size can only have a partial effect on the 

 restoration of the beds to their former productivity so long as there 



* Also as Sessional Paper XLVT., 1905. 



t I am indebted to Mr. Vaughan for the correct rendering oi many of the 

 Tamil names in this paper. The old spellings of the Sambore river and 

 Uppu-aru are retained in the text in place of the new official spellings 

 Sampur and Uppar, respectively. The Savarn is the same as Shava-arn on 

 the maps. 



F 8-07 



