58 DISCOVERY REPORTS 



A few records from South Georgia and elsewhere given by Hinton (1925) are also in- 

 cluded in the present analysis. If now the lengths of all recorded foetuses are plotted 

 against months the scatter-diagram in Fig. 53 is obtained. When the average lengths are 

 plotted by months the curve shown in Fig. 54 is produced. This shows that a pregnancy 

 starting in September terminates in the following August when the foetus reaches a 



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Aug-'' Sep ' Oct ' Nov ' Dec 'Jan ' Feb ' Mar Apr MaL| Jun Jul Aug 



Fig. 53. Humpback whale. Length of foetuses plotted against date of occurrence. 



length of about 4-5-5-0 m.., and that gestation takes about eleven months. The length of 

 the young at birth is taken as about the mean of the longest foetus and the smallest 

 recorded living young. From Fig. 53, on which the curve in Fig. 54 is superimposed, 

 it appears that the bulk of pregnancies start in the months August to November 

 inclusive, but the points below the average line in May and those far above it from 

 December to March inclusive show that, in addition, a small proportion of pregnancies 

 start in the months of December to June. Lactation will therefore take place from 

 August onwards : one lactating whale is recorded for December and one for March from 



