FORM AND GROWTH IN FISHES 



389 



formulae. Using length as the basis of comparison, each straight 

 line is, in general, represented by the equation 



y ^ ex -\- b 



in which y is the dimension of the body part (head, depth, etc.), 

 X is the length, while c is the 'slope' or 'tangent' of the line, and 

 b is the distance from the origin of the axes of coordinates to the 

 point where the line crosses the axis of ordinates. In all of the 

 lines given in these figures, b is practically zero, since the lines 

 all converge and meet at a point approximately (0,0), The 

 equation then becomes 



y = ex. 



In table 3 the values of c are given for each of the five measure- 

 ments for each species. Cynoscion regalis is included for com- 

 parison. 



TABLE 3 

 Values of the constant c 



The only reference to this sort of relation with which I am 

 acquainted is by Meek ('05), who showed that width and length 

 bear this simple straight-line relation to each other in the dab, 

 flounder, sole, and turbot. 



BODY MEASUREMENTS AND WEIGHT 



An attempt was made by Heincke et al. ('07) to find a relation 

 between body measurements and weight. They chose length 

 and depth, and found that 



g = U~d 



