LIFE-HISTORY OF AMPHIGONOPTERUS AURORA. 



203 



TABLE VI. 



THE COMPARATIVE SIZE OF THE SEXES IN AMPHIGONOPTERUS AURORA AND 



MlCROMETRUS MINIMUS. 



RATE OF GROWTH. 



The rate of growth of a fish which develops seasonal marks 

 on the scales can be readily computed with considerable accuracy 

 from the known length of the fish at the time of capture and 

 the measurements of one of its scales. The number of scales 

 remaining constant throughout life, the scale increases in length 

 along its horizontal axis in direct ratio to the increase in the 

 length of the fish. Thus for a fish of given total length, the 

 length attained at each winter, and consequently the growth incre- 

 ment of each successive year, may be computed by the use of the 

 following formula : 



length of fisli at the time of capture 



length of fish at winter x 



length of scale to margin 



length of scale to anniiliis formed in winter x 



