36 DISCOVERY REPORTS 



In several instances the whales of the lighter coloured groups, in which the ventral 

 groove area is white, had the ridges between the grooves white and the furrows of the 

 grooves black. Haldane (1905) notes this as occurring also in Shetland whales. 



Detailed information as to the development of colour in the foetus is not available, 

 as all the foetuses examined by the Discovery staff were small, none over 0-85 m. 

 in length. From foetuses of whales nos. 321 (0-64 m.), 2033 (0-51 m.), 3426 (0-4 m.), 

 however, it would appear that pigmentation starts dorsally on the head and upper jaw 

 and spreads towards the tail and ventral surface. 



True (1904) discusses the theory of Rawitz (1897) that the young whales are dark in 

 colour and become whiter as they get older, and agrees that the limited information 

 available to him tends to support it. The present series of whales, however, does not; 

 for the lightest coloured male is only 9-2 m. and the lightest female 9-5 m., in length; 

 while the largest male, 1475 m. long, and the largest two females both 14-9 m. long, all 

 belong to the colour group 4. 



The colour of the narrow ridge-like palate situated between the two sets of baleen is 

 white or very light greyish white, with nearly always a patch of darker grey pigment at 

 the posterior end of it. The tongue is white or very light grey. 



The general coloration of the southern and northern Humpback whales thus appears 

 to be the same, but unfortunately no data are available as to the relative frequencies of 

 occurrence of the various colour groups in the northern whales, so that no comparison 

 can be made between them and the southern whales, similar to that here made between 

 the South Atlantic and South African, and the New Zealand herds. 



Hinton (1925) points out the possibility of the differently coloured Humpbacks form- 

 ing separate races. He classifies his material into three categories, white bellied, marble 

 bellied, and black bellied, and finds that there are indications of slight differences be- 

 tween the three colour classes in some of their relative measurements. He points out 

 that the examination of further material is required before any definite conclusion as to 

 the existence of different races can be drawn. He deals with only a small number of 

 observations, and it must be admitted that the additional material discussed here gives 

 no grounds for supposing that any constant difference in relative dimensions is associ- 

 ated with any colour phase. The slight differences found in Hinton's material concern 

 chiefly the relative dimensions of the head and post umbilical regions, but as is shown 

 above these dimensions are a function of body length and consequently cannot be 

 correlated with differences in colour. 



On the other hand, there does seem to be some degree of segregation in colour, in that 

 certain colour classes occur in differing proportions in different localities, although 

 members of all classes appear to occur in all localities. As pointed out above, the South 

 Georgian and South African Humpbacks appear to be darker than the New Zealand 

 ones. Olsen (i 914-15) records that the black-bellied class is commonest at Port 

 Alexander, Angola and that this class is least common among the whales landed at 

 whaling stations of the northern hemisphere. He adds " a special feature of the southern 

 Humpback is that the flipper is nearly always dark coloured above, and of the above- 



