332 DISCOVERY REPORTS 



(a) Depende?icies of the Falkland Islands. 



South Georgia, 1913-25 15,535 Fin whales 



South Shetlands, 1918-24 ... ... ... 9)i53 x 



South Orkneys, 1922-26 ... ... ... 1,208 ,, 



(b) South Africa. 



Cape Colony, 1920-25... ... ... ... 2,131 <, 



Natal, 1922-26 1439 " 



Analysis of the figures gives the following results : 



(a) Dependencies of the Falkland Islands. 



Of all whales examined 54 per cent were males. 



Of 22 seasons in different localities there were six with from 51 per cent to 55 per cent 

 of females. The remaining sixteen seasons all showed a majority of males. Of these, 

 12 seasons showed 50 to 60 per cent of males, three seasons showed 60 to 70 per cent 

 of males and one exceptional season (1924-5 at the South Orkneys) showed as much 

 as 82 per cent of males. 



(b) South Africa. 



Of all whales recorded 56 per cent were males. 



Of 14 seasons in different localities only one showed a majority of females (54 per 

 cent). The other 13 seasons all showed a majority of males of which eleven fell between 

 50 and 60 per cent and two between 60 and 70 per cent. 



Here we have a more decisive result than in the case of Blue whales, males being in 

 an all-round majority both in the Dependencies and in South African waters. Our 

 own records agree with this, for 56 per cent of the whales examined and 54 per cent 

 of the foetuses were males. It seems difficult, therefore, to avoid the conclusion that 

 among Fin whales males are in a slight majority. Of all the Fin whales of which we 

 have records 45 per cent are females and 55 per cent males. 



As to the differences which exist between the sexes the male Fin whale becomes 

 mature on the average at 19-4 m., and the female on the average at just 20-0 m. Thus 

 there is approximately o-6 m. difference between the two, or the length of the male 

 is 97 per cent of that of the female. As in Blue whales the difference between the largest 

 specimen of each sex is even more marked, for the largest female measured 24-53 m. 

 and the largest male only 22-40 m., giving a difference of 2-13 m., the length of the 

 male being 91-3 per cent of that of the female. Thus it is on the whole probable that 

 there is an increased divergence in size after sexual maturity is reached. 



EXTERNAL PROPORTIONS 



A more or less complete series of measurements has been carried out on some 692 

 Fin whales, and the following table shows the average value of all the measurements 

 taken for male and female Fin whales, expressed as percentages of the total length. 



