WINDOW-PANE OYSTER. 233 



earliest and latest spawnings is impossible to say. My opinion is that 

 there would not be such a difference, and I believe these Kapalturai 

 oysters to be only slightly older than those of N achchikkuda , namely, 

 about 3 months. The locality has much to do with the size of the oysters, 

 and the last 2 years' work has shown that Kapalturai oysters are 

 healthier and larger than those from N achchikkuda. 



June, 1907. — Average of 16 specimens 6' 1 X 6*6 inches. Willey 

 computes their age at 3 years. 



/ believe they would be about 28 months, that is, in their third year. 



October, 1907.— Average of 15 oysters, 153 X 169 mm. (6-12 

 X 6 '76 inches). Willey considers them about 3| years old. 



My calculation would place them at 32 months, or about 2^ years. 



March, 1908.— Average of 22 oysters, 165 X 181 mm. (6 • 60 x 7 • 24 

 inches). 



These would be 37 months. 



Table III. — Kakkaimunai. 



May, 1905 (Hornell). — Two samples, one estimated by Hornell at 

 1^ year old gave average size of 102 x 111*4 mm. (4-08 x 4*45 

 inches) ; the other estimated at IJ year old gave an average of 

 114-96 X 125-2 mm. (4-59 X 5 inches). 



There may be a difference of a month or so in the ages of these two 

 batches. The smaller ones are about 15 months old. 



June, 1907. — Average of 12 specimens 111 x 119-3 mm. (4-44 

 X 4-76 inches). I cannot agree with Dr. Willey's conclusion that 

 these beloyuj to the same generation as HornelVs 1906 oysters. If 

 stunted growth is characteristic of the Kakkaimunai oysters, the 

 influences at work are not sufficiently powerful to keep half -grown oysters 

 at the same size for 2 years, between their fifteenth and thirty -ninth 

 months. I believe that these oysters were deposited early in 1906, that 

 is 1 year younger than HornelVs oysters. 



October, 1907. — 60 oysters, having an average size of 123-87 X 

 133-25 mm. (4-95 x 5-33 inches). 



These were undoubtedly oysters of the second year, about 20 months 

 old ; that is to say, they were probably the same batch of oysters that 

 were measured in June. 



79 oysters were measured, the smallest being 92-75 X 106 - 25 mm. 

 (3-71 X 4-25 inches), and the largest 146-9 x 159-4 mm. (5-87 X 

 6-37 inches). 



These 79 samples evidently contain oysters of three different years. 

 The smallest ones are undoubtedly 8 months old, and the largest are 

 probably 32 months old. We would gather from this that the majority 

 of them would be second-year oysters, about 20 months old, deposited in 

 1906. 



March, 1908.— Average of 16 "topotypes," 122-1 X 129-2 mm. 

 (4-88 X 5-61 inches). These appear to be second-year oysters, about 

 14 months old, and belong therefore to a 1907 brood. 



