1880.] MR. R. COLLETT ON BAL.ENOPTERA BOREAHS. 251 



The oblong whitish marks occurred all over the animal, from the 

 beginning of the flippers to the root of the tail, but did not, generally 

 speaking, extend much higher than the middle of the sides ; several 

 small spots, however, of normal form occurred up towards the back. 



In this specimen the underside of the flippers had large whitish 

 spots. 



No. 4. A male. — Unusually dark. The white colour was com- 

 paratively little extended, as in front it embraced only four furrows 

 on each side, and even here was mixed with black. Backwards the 

 white colour widened somewhat, so that six furrows on either side 

 were included, though with black stripes from the sides extending 

 obliquely into them. Behind the furrows the central patch was ter- 

 minated by the colour of the sides, and there was but little white in 

 the portion in front of the genitalia. 



In this specimen were noticed a large number of the peculiar oblong 

 marks, some quite white, most of them, however, darker in hue, 

 spread over .ill the dark parts of the belly, extending both downwai'ds 

 to the white stripe and upwards on to the back. They were most 

 numerous about the middle of the sides and on the posterior portion 

 of the body. 



No. 5. A male. — Throat white, extending over eight furrows 

 on each side, from the front to between the ends of the flippers. 

 Above these, six furrows on each side were mottled with white. 



Further back the white part was interrupted, so that the belly 

 behind the furrows was, for a short distance, of a uniform blue-grey 

 tint like the sides, but again became whitish, sprinkled over with the 

 narrow bluish lines as far as the genitalia. The oblong whitish 

 marks were present, especially on the sides. 



No. 6. A male. — Colour almost similar to that of No. 2, the white 

 having almost exactly the same extent. Here also the white patch be- 

 tween the flippers extended in a somewhat irregular anchor-like form. 

 Behind the furrows the white was almost terminated by the bluish- 

 grey colour of the sides ; it recommenced at the navel and extended 

 to the genitalia, but was pencilled over evenly by fine short grey 

 lineolse. The oblong whitish marks were numerous, tolerably light- 

 coloured, but none quite white, and extended almost to the end of 

 the loner jaw. 



In a 7th specimen, which lay secured in the water with the belly 

 exposed, the white colour was more decidedly asymmetrical than in 

 any of the others. On the breast the white included six furrows on 

 the right side, whilst ihe whole of its left side was black '. 



The white area extended as usual to behind the end of the flippers, 

 where it became narrow or disappeared, but extended again back- 

 wards to the genitals, and at this point it was symmetrical on the 

 two sides. 



' A similar asymmetry of colour (left side dark, right side white) has heen 

 noted on two occasions by Professor Sars as pervading the lower jaws in B. nms- 

 culus (Forh. Vid.-Selsk. Christiania, 1878, no. 15, p. U ; 1880, no. 12, p. 3). [A 

 similar specimen was recorded by me in the 'Zoologist,' April 1885, p. 138. — 

 A.H.Cl 



17* 



