242 



SPOLIA ZEYLANICA. 



Appendix 10.— Measurements of Second-year Oysters, September, 1912. 



(vSee also Plate 9.) 



Size (Hinge 



Diameter). 



Inches. 



4i 



H 



*8 



4i 



4| 



5 



5i 



No. of 

 Specimens. 



3 

 3 

 4 

 5 

 14 

 5 



Size (Hinge 



Diameter). 



Inches. 



5i 

 5f 

 5i 



Total specimens . 



No. of 

 Specimen.'?. 



4 

 4 

 1 

 1 



45 



Explanation of Plates. 



1 Placuna shells showing evidence of having been bitten by fishes 



X h 

 2. Map of Lake Taniblegam, showing the distribution of oysters in 



September, 1912, and also the division of the lake into areas. 



Scale 1^ inch to 1 mUe. 

 :k/. Map of Lake Tamblegam, showing the distribution of the 1911 



oysters before the rains. 

 86. Map of Lake Tamblegam, showing the distribution of the 1911 



oysters after the rains. Scale | inch to 1 mile. 



4. Comparison of the sizes of 1912 oysters in each area for May, 



June, and September, 1912. 



5. Curve showing rate of growth of Placuna during 3 years. 



6. Curve showing sizes of 1912 oysters in May, 1912. 



7. Curve showing sizes of 1912 oysters in June, 1912. 



8. Curve showing sizes of 1912 oysters in September, 1912. 



9. Three curves showing sizes of 1911 oysters in January, June, and 



September, 1912. 



