THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 127 
The color of the pectorals is normally gray on the external surface, like the 
back, and white on the internal surface and anterior border. 
In some Newfoundland specimens the dark-gray external surface was more 
or less marked with lighter gray, and the light-gray area at the root of the pee- 
toral, already described (see p. 121), sometimes invades the pectoral, so that the 
proximal 4 of the external surface may be abruptly and conspicuously lighter 
than the remainder. The light area may be defined posteriorly by a dark gray 
line running across the pectoral to the axilla and thence to the back. 
The anterior thick margin is always white, but this color in some instances 
extends much farther upon the external surface of the fin than in others, especially 
at the tip. The margin itself is usually more or less streaked with gray, and in 
some instances is entirely gray for some distance from the root of the fin, or there 
may be a gray patch near the middle of the border. 
The internal surface of the fin is sometimes entirely white, or with but a narrow 
posterior border of gray, but in most cases the posterior two thirds shade more or 
less into gray, especially toward the tip. The tip underneath is commonly marked 
with gray lines, either parallel or reticulated. In the majority of cases there are 
one or two long gray lines running backward from the tip parallel with the long 
axis of the fin, and corresponding in position with the intervals between the digits. 
These lines are of so frequent occurrence as to be characteristic of the species. 
FLUKES 
The flukes in the Newfoundland Finbacks (pl. 12, figs. 7-8) were long and 
slender, with acuminate and strongly recurved tips. The anterior border is convex, 
the posterior slightly convex near the median line, then nearly straight, and finally 
strongly concave at the tips. The median notch was shallow and more or less 
open in different individuals. 
The flukes are gray on the superior surface, like the back. On the inferior 
surface they are all white, except on the margins. The posterior margin is gray 
throughout ; this color, however, having a wider extension distally than proximally. 
The anterior margin is gray distally, but the white usually invades this margin 
proximally. The tip is gray. Near the median line the posterior gray border is 
about 7 in. wide and the anterior 2 in. or less. The gray borders fade out into 
streaks which run transversely, or as if radiating from the end of the spine, and 
this arrangement doubtless gave rise to the erroneous fish-like tail, with rays, seen 
in some early figures. The transverse streaks on the anterior margin are crossed 
by others running fore and aft, especially near the root of the flukes. (See also 
pl. 12, fig. 5.) 
WHALEBONE, 
One of the principal characters of B. physalus, which was early recognized, 
is the party-colored whalebone. Later it was discovered by Sars and others that 
the whalebone of the anterior end of the series of the right side is always white. 
