1913] Michael: Snglffa califoniira froni San Diego Reyion 111 



AA'hile the correlation coefficient is negative ( /•=-- — 0.0858), 

 thereby indicating that the body increases in length faster than 

 the tail, the probable error is relatively so large (=0.0656) that 

 this appearance is most likely due to chance. It is evident from 

 inspection of the table that the majority of animals between the 

 lengths of 20 and 26 mm. have tails lying between 27 and 28 per 

 cent. Furthermore the next most abundant number have tails 

 lying between 28 and 29 per cent. Moreover, when the average 

 lengths for the tail corresponding to each group of animals are 

 calculated they show more clearly the absence of any definite 

 correlation. Such averages are as follows: 



27.9 ]per cent for entire jioimlation (12-26 mm). 

 27.6 per cent for animals between 24 and 26 mm. 



27.1 per cent for animals between 22 and 24 mm. 

 27.9 per cent for animals between 20 and 22 mm. 



27.2 per cent for animals between 18 and 20 mm. 

 27.8 per cent for animals between 14 and 16 mm. 

 27.-5 per cent for animals between 14 and 16 mm. 

 29.0 per cent for animals between 12 and 14 mm. 



Thus, excepting those animals between 12 and 14 mm., the 

 average length of tail lies between 27 and 28 per cent, irrespec- 

 tive of the length of animal. It is quite probable, therefore, 

 that, between the lengths of 14 and 26 mm., the tail grows as 

 fast and no faster than the body, thereby maintaining a constant 

 proportion. 



Remaining Proportions. — As in the case of the tail, no 

 definite correlation between variations in length of auinuil and 

 variations in the remaining proportions was found. It seems 

 unnecessary, therefore, to consider each in detail. Instead the 

 correlation coefficients relative to each proportion, given below, 

 show clearly the absence of definite correlations : 



Proportions Coefficients 



Interval from tail to ventral ganglion ?• = — 0.1403 ±0.0.53 



Length of anterior fin r= +0.1.54 ±0.096 



Width of anterior fin r= +0.0931 ±0.06.56 



Anterior fin to ventral ganglion r:^ +0.148.5 ±0.0647 



Length of posterior fin )•= +0.03.53 ±0.0661 



Width of posterior fin r= +0.0679 ±0.066 



