ASSORTIVE MATING IN CHROMODORIS ZEBRA 



261 



TABLE 3 



TABLE 4 

 Correlation, between the volumes of members of 66 pairs of C. zebra', r = 0.135S 



pend upon the condition of the gonad and associated reproductive 

 glands; perhaps in some additional manner the volume of an 

 individual may be a function of the number of egg masses which 

 the nudibranch has recently deposited. If this interpretation be 

 correct, it follows that length (and correlated external dimen- 

 sions), rather than reproductive condition (provided the animals 

 in question be still capable of being stimulated to copulate), is 

 the basis of selection in pairing. This would explain the low cor- 

 relation for homogamy in the volume series of measurements (al- 

 though the small number of cases may be responsible), and would 

 be intelligible in view of the irregular relation between vokune 



