172 



ALBERT C. EYCLESHYMER. 



on the postero-ventral surface of the first bar, midway between its 

 base and apex ; soon a second filament appears on the antero- 



Q 



8 



e 



9 



H. 



a ff 



zzr 



I 3 



FIG. I. Each series is bracketed and designated by Roman numerals. The upper 

 row in each series represents the changes in the normal gill. The lower row of each 

 series represents the changes in the regenerating gill of the same larva. The nume- 

 rals indicate the days of the month : June 16-30 and July 1-17. All the figures are 

 magnified about ten times. 



ventral surface opposite the first, as shown in Ser. II., Fig. 19. 

 Often the buds form at different levels, giving rise to unsymmet- 



