1893.] 



Correlated Variations in Carcimis moenas. 



323- 



Table II. Distribution of lengths of Antero- lateral Margin of Cara- 

 pace in 999 Female Carcinus from Plymouth. 



the smallest numerical value of any in general use; This property 

 renders the probable error more convenient than either the mean 

 error, the modulus, or the error of mean squares, in the determination 

 of the degree of correlation which will be described below. 



Table III. Mean Length and Probable Error of Various Parts of 

 Carcinus moenas in Naples and Plymouth, in thousandths of the 

 Carapace length. 



