COMMON FINBACK WHALE. 181 



and the pectoral fin and above and below the root of the latter. The breadth of the abdominal 

 ridges is about two inches near the middle of their length, and twice that posteriorly. 



Color. — As seen in life at close range, the general color of the Finback above, is dull gray- 

 ish brown (sepia, as the artist Millais says, passing into brownish gray on the flanks). This 

 rapidly darkens after death, and becomes quite black after a short exposure, a fact which has 

 led to some misconception as to the true color. The lower surfaces of the body, including the 

 ventral side of the pectorals and flukes, and also the right mandible and more or less of the 

 right-hand side of the upper lip, are white. The line of demarcation between the dark of the 

 upper side and the white of the belly, though fairly well defined, is most irregular, and the one 

 passes gradually into the other at the sides. On the left-hand side of the body, the dark color 

 commences usually at or just back from the point of the jaws, and extends part way, often 

 nearly to the midline, including the summits as well as the troughs of the plicae laterally, but 

 the troughs alone more ventrally, while in the mid-region of the lower side these furrows too 

 are white. Just in advance of the pectoral there is usually a darker tongue or two of color 

 passing ventrally, where both ridge and trough of the phcae are pigmented over a narrow area. 

 A somewhat similar tongue of dark color may be present behind the pectoral, invading tlie 

 whitish of the sides. There may also be irregular dark blotches like islands on the sides of 

 the throat, and usually one just behind the anus. 



Usually a light marking, ill defined, from the region of the ear opening of the right side, 

 "curves strongly upward, then downward, and terminates at or above the anterior insertion 

 of the pectoral fin. On the left side another light line usually starts at the eye, and may run 

 under or through rather than over the ear, and terminate at the insertion of the pectoral" 

 (True, 1904, p. 124). 



Most remarkable is what appears to be a definite and constant asymmetry, in that the 

 right mandible, and commonly the tip of the right side of the snout are white. Even the whale- 

 bone plates at the anterior end of the right side are likewise white. It should he added that 

 the white of the lower surface of the pectorals may extend around to their front edge or tip, 

 but that on the flukes the white does not quite reach the margin ventrally. 



Variations.-^ A number of specimens are described in detail by True (1904, p. 121) to 

 show the individual variation in color pattern. Some seem paler than others, due to the vary- 

 ing degree to which the gray areas encroach on the belly and throat, or the presence of streaks 

 and patches of darker color about the anus or the median line of the peduncle. The white 

 of the right side of the head may include the entire lip from the tip of the snout to the angle 

 of the mouth, or it may be confined to the anterior third or fourth. The post-anal gray mark, 

 may in some cases be nearly obsolete. In one instance the white of the right side of the head 

 was so extensive as to exclude all gray color from the ridges in front of the pectoral. On the 

 left side, the mandible is usually dark nearly to its tip but the white may extend to about the 



