256 



W. J. CROZIER 



should be noted, further, that there is no detectable tendency 

 for individuals of any given size to copulate at a different time 

 of day, or season, from those of any other size. 



One hundred and forty-eight pairs gathered in Fairyland 

 Creek were composed of individuals giving the length-frequency 

 distribution exhibited in figure 7. The relation between the 



8- 



6 - I I 



4 - ,- I 1 



2 -| 1^ 1 '""" 



e 9 10 II \Z 13 14 15 16 cms. 



6 3 10 II \l 13 14 15 16 ms. 



Figs. 5 and 6 The frequency distribution of sizes (total lengths) for mating 

 and non-mating individuals in two random collections (Apr. 24th and Apr. 30th, 

 respectively); the continuous line denotes mating individuals, the dotted line 

 non-mating individuals. Showing that there was no significant difference be- 

 tween the sizes of mating and of non-mating specimens. 



lengths of the two individuals constituting a pair is set forth in 

 table 1. This is a single-entry correlation table, constructed and 

 used in accord with the manner suggested by Jennings ('11 a, 

 '11 b) for cases of this kind. The coefficient of correlation is 

 found to be 



r = 0.608 ± 0.0247 



