1386.] MR. R, COLLETT ON BALHNOPTERA BOREALIS. 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. 
at 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 all the dark parts of the belly, extending both downwards 
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. 4 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 
lineolee. The oblong whitish marks were numerous, tolerably light- 
coloured, but none quite white, and extended almost to the end of 
the lower 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 the 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 been 
noted on two occasions by Professor Sars as pervading the lower jaws in B. mus- 
culus (Forh. Vid.-Selsk. Christiania, 1878, no. 15, p. 9; 1880, no. 12, p.3), [A 
imi pinke was recorded by me in the ‘ Zoologist,’ April 1885, p. 138.— 
iz 
