44° 



DISCOVERY REPORTS 



part of the curve (representing the specially large whales). This, approximately, is the 

 result obtained among Fin whales (Fig. 153). The difference between the two maxima 

 represents roughly the normal difference in length between the sexes. 



When we turn to the Blue whales we find that some of the curves are of quite an 

 unexpected shape. In the 1926-7 season, when the majority were fully grown, the 

 curves are of the normal type found in Fin whales with one marked apex for each sex, 

 but in the preceding seasons the curves tend to resolve themselves into several apices 



45- 

 40- 

 35- 

 30- 

 25- 

 20- 

 15' 

 10- 

 5- 



0- 



30- 



►j25- 



< 

 D 



220H 



Q 

 Z15- 



'10- 



ca 5- 

 S 



D 



2 0. 



S. GEORGIA 192G-7 



19 20 21 22 23 Ti 25 26 ^^ 28~ 



/ \ 



^^J 



15 16 17 



LENGTH GROUPS (METRES) 



28 



Fig. 152. Blue whales (continued). Length frequencies for different periods. 

 Females. Males. 



of comparatively uniform prominence. Perhaps the best example is furnished by the 

 figures for males and females in the half-season February to May 1925. There are three 

 maxima for each sex showing that males are commonest at 18-19 "^•■> 21 rn. and 24 m. 

 and less numerous at 20 m. and 22-23 "^-i ^^i^ that females are more numerous at 

 20 m., 23 m. and 26 m. and less numerous at 21-22 m. and 24 m. In other words 

 these whales tend to approximate to one of three different sizes which may be regarded 

 as (i) small immature (18-19 m. in males, 20 m. in females), (2) large immature (21 m. 



