158 



DISCOVERY REPORTS 



in low latitudes, among whales which have remained behind, at the same time as among 

 those which have migrated. 



It has been suggested that the old bulls which migrate by themselves into high lati- 

 tudes are old ones which have been driven out of the schools by younger and more 

 vigorous ones. The latter part of this hypothesis appears to be likely because they are 

 nearly all of large size, but examination of the state of ankylosis of the epiphyses of the 

 vertebral column reveals the fact that they are by no means always fully adult, in fact the 

 majority have not reached complete physical maturity, and they, therefore, cannot be aged 



in 



Total Length in metres 

 Fig. 67. Sperm whale. Length frequencies. 



individuals. The large size of South Georgia males compared with that of those taken off 

 South Africa is well shown in Fig. 67. It is of interest to note that a female Sperm whale 

 was captured off South Georgia in November 1925, and a newly born young one was 

 thrown ashore off the west of Ireland in September 1916, showing that very rarely the 

 female Sperm whale strays into high latitudes with the males. Salvesen (19 14) gives a 

 photograph of a Sperm whale on the flensing plan at Leith Harbour, South Georgia, 

 and labels it as a female. It is not a female, however, but a male with the penis not 

 extruded, as is shown by the separate genital and anal apertures. Its size in comparison 



