234 SPOLIA ZEYLANICA. 



Average of 16 oysters, which were transplanted to Naehchikkuda 

 in October, 1907, 130-1 X 141-8 mm. (5-20 x 5-67 inches). 

 These are evidently oysters deposited in 1906, about 26 months old. 



Table IV. — Sembian-aar. 



May, 1905 (Hornell). — Numerous oysters. Average size 142-25 

 X 155 mm. (5*69 X 6-20 inches). Hornell states that these are 

 " probably over 2 years old." 



In my opinion they are about 27 months old. 



June, 1907. — Average of 12 oysters, 142-5 X 150-5 mm. (5-70 

 X 6-02 inches). Willey believed that these were the same brood 

 examined by Hornell in 1905, and that growth was suspended for over 

 2 years. This is diflficult to believe, especially as the same batch of 

 o3^sters showed an increase in growth 4 months later, and a further 

 increase 9 months later. In fact, the oysters measured in June 

 and October, 1907, and March, 1908, appear to me to be slightly 

 undersized oysters of the 1905 brood, and are hence 2 years younger 

 than those measured by Hornell in 1905. 



In June, 1907 , they were probably 28 months old. 



October, 1907. — Average of 20 oysters, 149 x 154 mm. (5-76 X 

 6-16 inches). 



These are the same batch as those examined in June, and are probably 

 32 months old. 



March, 1908. — Average of 20 oysters, 154-75 X 166-4 mm. 

 (6-19 X 6-65 inches). 



Probably 37 months old. 



Table V. — Poloharai-aru. 



October, 1907.— Average of 18 oysters, 149-6 x 154-7 mm. (5-98 

 X 6-18 inches). 

 These are some of 1905 brood, and are about 32 months old. 



Transplanting. 



Transplantation experiments have been in progress for some time. 

 In the 1911 inspections full-grown pearl-bearing oysters were found 

 in Naehchikkuda, which were the remnants of the oysters trans- 

 planted by Dr. Willey. His experience led him to believe that 

 transplantation was not successful in the case of oysters a few months 

 old. But this is the period when transplantation is most necessary. 

 I have found 3-months and 6-months oysters in great profusion 

 near the shore along the southern boundary of the main bed. So 

 abundant were they in May of this year that the divers were able 

 to bring up about twenty or more in a few seconds at a station a 

 few hundred yards west of Kodaipota. In areas K and J the oysters 

 were overcrowded during the Maj^ inspection, and to a less extent 

 in September. Owing to the rapid growth of the young oysters 

 there must be a great mortality through, overcrowding in the first 



