250 MR. R. COLLETT ON BALZNOPTERA BOREALIS. _ [ Feb. 2 
long axis there runs a dark line, from which to both sides and both 
ends run fine radii of similar lines '. 
These patches are most frequent on the sides of the body some- 
what below the middle, and occur also on the tail, but may be found, 
when they occur to any great extent, distributed singly right up the 
centre of the back, and extending as far as the end of the lower jaw. 
They occur on all examples, although they may not be equally 
apparent in all. They evidently are due to a peculiar matter in 
the skin, as they become more perceptible after the animal has 
dried for a time. Single small white spots of a normal form occur 
less frequently in the black portion of the sides, especially up to- 
wards the back. 
Among the markings of less constant occurrence may be 
noticed :—-On one of the specimens examined there was a slightly 
lighter patch behind the ear-opening, which began just at its pos- 
terior margin, and extended backwards in a pyramidal form for 
about a foot. 
In order to show the variations of the white colour on the belly, I 
shall briefly explain its extent in the individuals examined by myself. 
No. 1. A female.—Throat entirely white ; on the breast the white 
area became narrower, though without being completely broken 
off. A larger white patch “occurred at the end of the furrows, 
forming here an extension of the central stripe. On the belly the 
white colour was partly covered over by the fine light bluish-grey 
lines, which terminated as single white stains at the mamme. 
No. 2. dA female.—The white area symmetrical and ample; 
throat white, about ten furrows on each side being included, though 
the upper ones were spotted with black. 
The patch became narrower backwards, so that between the 
flippers only three furrows on each side were included, while behind 
the flippers it spread out in an anchor-like form, the arms of which 
extended rather high up on the sides (and to about half a flipper’s 
length from the end of the flipper). 
Behind the furrows the white area was almost interrupted by the 
grey colour of the sides, but widened out again in front of the 
mammee, where it was whitish and not sharply defined. The fine 
bluish-grey lines were most frequent towards the dark portions of 
the sides. 
In this specimen the oblong whitish marks on the sides were com- 
paratively few and indistinct, “although some of them were perfectly 
white. 
No.3. 4d female.—Throat white, the white commencing just 
behind the symphysis of the jaw, and including the eight furrows on 
each side of the central line; this white portion cvacished as it 
passed backwards. Almost exactly under the distal end of the 
flipper, when lying parallel to the body, it was broken off by the 
colour of the sides} but it recommenced at the navel, and thence 
extended unbroken to the mamme. 
? The general form and design reminds one of the septa ina Fungia or 
Herpetolithus. 
