I02 



DISCOVERY REPORTS 



Table XXXVIII. Average percentage occurrence of the sixth Fur cilia 



It is seen that there is a decrease from August to December from a stock three-quarters 

 of which are Furcilia 6 to one in which this stage is not represented. 



AUG 



SEPT OCT NOV DEC JAN 



Fig. 27. Average length of second season krill. The smaller signs express average lengths of individual 

 samples, the larger ones the half-monthly average lengths of all the young euphausians taken. 



An impression of the length range of Furcilia 6 is easily obtained by reference to the 

 appendix. The way in which the upper limit of length overlaps the lower limit of the 

 adolescent size range emphasizes the indefinite nature of the division between the two 

 phases of developmental history. The length range of Furcilia 6 covers 9 mm., extending 

 from 8 to 17 mm. with a mean length of about 12 mm. But it is possible to get ado- 

 lescents 10-5 mm. long, so that there is an overlap in the two length ranges of 6-5 mm. 



In Fig. 27 the average lengths of the krill from the samples referred to above are de- 

 picted. The smaller signs express average lengths of individual samples and the larger 

 ones the half-monthly average lengths of all the young euphausians taken. The three 

 seasons' catches have been given the designation of classes, that is to say the 1927-8 

 class represents larvae which originated in that season. They would be adolescents in 

 the 1928-9 season and adult in the succeeding season. 



