THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 291 
third was shining black, but the remainder all snow-white. The anterior border 
was thick and rounded, but irregularly emarginated and covered with numerous 
examples of Coronula diadema ; the hind margin sharp and entire. 
“The dorsal fin was shining black. 
“The flukes were black on the upper surface, with a number of scattered, 
irregular snow-white spots; on the lower surface, the ground color of which was 
shining black, these snow-white spots were more numerous. The anterior border 
of the flukes was thick and rounded, the posterior margin, strongly emarginate and 
occupied by many examples of Coronula diadema. 
“The whalebone was all gray-black.” 
Rawitz (74, 89) states that the whalers account for the variation in color on 
the basis of difference of age. “'They say that young animals have a black ventral 
skin, and the old ones a white skin; the former have little blubber and the latter 
much.” He is inclined to accept this explanation, as the four specimens he exam- 
ined seem to support it. He remarks: “We should have then, were this explana- 
tion correct, the highly interesting physiological phenomenon before us, that with 
increasing fat in the corium (wnterhaut), the pigment in the epidermal cells 
completely disappears.” 
In order to test this theory I have arranged below the 13 specimens from dif- 
ferent parts of the North Atlantic in the order of size, the smallest first. In the 
table, the letter W signifies that a part is white, V signifies that it is varied, part 
white and part black, and B signifies that it is entirely black, or substantially so. 
MEGAPTERA NODOSA (BONNATERRE). EUROPEAN AND AMERICAN. COLORATION. 
Color of Pectorals. | Color of Flukes. 
Autt aus Total Color of | Color of | Color of 
PURE vex: Length. Throat. | Breast. Belly. 
Above. | Below. Above. Below. 
Cocks ace 30' 0” B B B W W is ae 
Rawitz 2 34 5" B B B B W B W 
Cocks rs) BEMOn B B B W W 
Struthers }$ 38! 0” B B B a W ws W 
Cocks Brete 40! 0” W a a B WwW a Ww 
Rawitz $ 41’ 0” B B B W W V W 
3 rs) 41’ 8” V V V W W Vv W 
Cocks } 42' 0” W W B W oe Ss a6 
True é Aa! ae V Wi B W W B W 
Cocks eters 44' 0” B V B +B W ae Be 
True 2 As uase W V B +B W B W 
4 & 46! 6" Vt 3 B WwW W ae 36 
Rawitz 2 46' 9” W W W W W W Ww 
Assuming that the thirteen specimens belong to the same species, the fore- 
going table lends some support to Rawitz’s theory, as the youngest specimens all 
have the throat, breast, and belly entirely black. It will be noticed, however, that 
my Newfoundland females, which were adults, were but little white, so that it 
would appear that whiteness is not invariably assumed by mature individuals, and 
may be rather a sign of senility. There is probably a considerable individual 
variation in this regard, as there certainly is in other genera. Rawitz’s largest 
