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Show 1886.] MR. R. COLLETT ON BALtfiNOPTERA 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. No. 4. A male.-Unusually dark. The white colour was comparatively 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 terminated 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. A male. - Colour almost similar to that of No. 2, the white having almost exactly the same extent. Here also the white patch between 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 lineolae. 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 backwards to the genitals, and at this point it was symmetrical on the two sides. 1 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. musculus (Forh. Vid.-Selsk. Christiania, 1878, no. 15, p. 9 ; 1880, no. 12, p. 3). [A similar specimen was recorded by m e in the ' Zoologist,' April 1885, p. 138.- |