3S6 



DISCOVERY REPORTS 



It is evident again that considerable individual variation takes place, but in this case 

 the path of the plotted points indicates that the plates increase in length quite uni- 

 formly, at any rate from 14 m. onwards. Therefore if there is any sudden spurt in the 

 rate of growth of the baleen in young Fin whales it must be supposed that it takes 

 place before the whale reaches 14 m. It is fairly certain that this spurt in growth 

 takes place in Blue whales and it is consequently very probable that something of the 

 same sort occurs in Fin whales. The curve representing the mean rate of growth of the 

 baleen plates is therefore drawn as a continuous line for whales of more than 14 m. 

 and as a dotted line for the smaller whales where its shape depends rather on analogy 

 with Blue whales. This dotted line is intended to represent the most probable course 

 of the rate of growth, the suggestion being that the rate suddenly increases when the 

 whale measures about 13 m. 



The numbers of baleen plates in Fin whales are on the average greater than in Blue 

 whales. The records may be tabulated as follows: 



Fin Whales 



The above table gives an idea of the limits within which the numbers of baleen 

 plates may be expected to vary and shows that there are no grounds for drawing any 

 distinction between males and females, or between the whales of South Georgia and 

 South Africa in respect of this particular character. 



Observations on the baleen of Fin whales have also included the counting of the 

 numbers of white plates (i.e. plates whose outer edges are white) on the right-hand 

 side of the mouth. The results, analysed in the same way, are as follows: 



