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W. J. CROZIER 



10 



)8 IV 16 15 14 13 12 



13 



50 40 



30 



20 



10 



Fig. 10 Regression plot for data in Table III; r' = regression line as calcu- 

 lated from "mantle-length;" r, same as calculated from "total-length" meas- 

 urements for the same 89 pairs. (See text.) 



Fig. 13 Regression plot for correlation in volume between members of 66 

 mating pairs (see Table IV). The regression is probably not strictly linear (cf. 

 Fig. 8). The unit of classification is 5 ccm. 



