THE SPERM WHALE 119 



surface of them. In 28 per cent light flecks were also present on the sides of the dorsal 

 hump. On the ventral surface of the tail a light grey or white post-anal marking 

 occurred in 7 per cent (Plate III, fig. 3). 



The lower jaw was frequently white or very light in colour ; in some cases dark pig- 

 ment was present in the median line but failed to reach the alveolar margins, while in 

 others the whole jaw from the gape was unpigmented (Plate III, fig. 3). A wholly or 

 partly white jaw occurred in 17 per cent, while in a further 20 per cent the upper lips 

 and alveolar margins of the lower jaw were sufficiently unpigmented to appear white 

 when the mouth was closed (Plate VI, figs. 1-3; Plate VII, fig. 2). 



A white marking occurred on the front surface of the head in 25-6 per cent of Sperm 

 whales. This marking took the form of a series of white and dark flecks and streaks 

 arranged in a spiral fashion converging on a central point in the light area (Plate V). 

 This head whorl appears to be the marking referred to by Beale (1839) : " ' old bulls ', as 

 the fully grown males are called by whalers, have generally a portion of grey on the nose 

 immediately above the fore part of the upper jaw, and they are then said to be ' grey 

 headed'." The marking is not confined to old bulls, however, as it was present in two 

 small males, 13-6 and 13-9 m. long, and in two females, lo-i and io-6m. long, at Durban, 

 as well as in larger bulls at Durban and South Georgia. 



In the foetus pigmentation starts before a length of 0-5 m. is reached. At this stage 

 the colour is pink and the unpigmented areas are paler. They occur on the sides and 

 under surface of the head and as pale lines extending from the dorsal hump to the notch 

 of the flukes and from the genital groove to the anus. At 1-5 m. in length the dorsal 

 pigmentation has become brown, and the ventral surface, sides of head and lower jaw 

 are creamy yellow. Light areas occur on the tail behind the anus and on the under sur- 

 face of the flukes. At 2-5 m. in length the pigment has become slate grey but has not 

 extended much in area, while at 3-1 m. the dorsal coloration of each side joins ventrally 

 between the anus and the flukes, the rest of the ventral surface still being white or light grey. 



Pigmentation thus starts dorsally and extends down the sides to meet ventrally, the 

 sides of the head, the lower jaw and the under surface of the flukes, being late in receiving 

 their pigment. The white umbilical splash, the umbilical whorl, the light coloration at 

 the genital groove, the white lips and lower jaw frequently occurring in the adult are 

 therefore probably congenital, and due to irregularities in the extension of the pigmented 

 areas and not to age. In this connexion it is of interest to note that in the calf Sperm 

 whale 4-04 m. in length, probably recently born, described from Bermuda by Wheeler 

 (1933), there was a large white umbilical splash, and the fleckings of the umbilical whorl 

 extended some way up the flanks and round the genital aperture to coalesce behind it. 

 The area covered by the umbilical whorl in this calf appears to be larger in proportion 

 than in the adult and points to the possibility of further extension of dark pigment after 

 birth. 



On the other hand, the whorl on the front surface of the head was not noted in any 

 of the foetuses examined, and it may therefore possibly be developed later in life, 

 although it cannot be taken as a sign of old age as suggested by Beale (1839). 



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