LIFE-HISTORY OF AMPHIGONOPTERUS AURORA. 



201 



COMPARATIVE SIZE OF THE SEXES AT DIFFERENT AGES. 



Scales were retained from numerous specimens of Ajnf>hi- 

 gonoptcru*; aurora of measured length, all obtained near Piedra? 

 Blancas, California, on June 2 and 4, 1916. Excepting a few 

 selected to represent extreme sizes, these were chosen at random 

 from the large number collected. The annuli, discussed above, 

 are well developed on these scales, their number indicating the 

 approximate age of the fish (the time of intramaternal develop- 

 ment, about one half year, being arbitrarily excluded). Thus the 

 presence of a single annulus, in addition of course to the natal 

 annulus, indicates that the fish was born in the preceding summer, 

 and that it is just completing or has just completed, the first year 



TABLE IV. 



LENGTH TO CAUDAL BASE OF FEMALES OF AMPHIGONOPTERUS AURORA OF 



DIFFERENT AGES. 



