Figure 6. — Sea scallop shell with five prominent annual 

 rings. The shell between the rings shows annual 

 attacks by boring organisms. 



Figure 7. — Cross section of hinge of sea scallop showing 

 annual marks in the calcareous plates of the resilium. 



Figure 8. — Calcareous plate of a resilium showing banding 

 and constriction in response to some annual stress. 



time and location but which had been at large 

 from 48 to 68 weeks before being recaptured. 

 These shells were grouped by 2-week intervals, 

 and the length when tagged (L s ) and the length 

 when recaptured (Z, r ) measured on each one (table 

 2). The Walford (1946) regression of length at 

 recapture on length when tagged was then cal- 

 culated for each of the five groups. The tabula- 

 tion below shows the number in each sample, the 

 time at large, and the slope and intercept of the 

 regression equations. 



ANNUAL MARKS ON SHELL OF SEA SCALLOP 



305 



