THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 129 
ABDOMINAL RIDGES AND FURROWS. 
In B. physalus the abdominal ridges and furrows are broader and less numer- 
ous than in B. acuto-rostrata, much narrower and more numerous than in the Hump- 
back. They are parallel for the most part, but anastomose frequently at different 
points. Sars’s description of the furrows in an European (Lofoten Ids.) specimen is 
as follows (77, 18 and 14 sep.) : 
“The breast furrows, which are very characteristic of the fin-whales, occupy 
the whole of the anterior half of the ventral side of the animal, from the tip of 
the mandible to the navel. In the present species they are quite numerous 
and extend well up on the sides of the body. In a straight line around the 
ventral surface about 70 furrows may be counted. The middle ones extend far 
backward to the very sides of the navel; the others become little by little shorter 
upward, so that the posterior boundary of the furrowed area on the sides forms a 
line passing obliquely from the navel to the root of the pectoral fin. These fur- 
rows as a whole run nearly parallel with the long axis of the body and each other, 
but are often interrupted, so that a new one takes its origin a little in front 
of the place where another ends. On the sides of the neck, or between the 
corner of the mouth and the root of the pectoral, the furrows extend farthest up 
on the side of the body, and their course is here less regular. From the corner of 
the mouth, four short furrows run backward and are somewhat sigmoid, and one 
approaches near the root of the pectoral. From the root of the mandible run 8 
furrows of unequal length, which converge posteriorly without reaching the root of 
the pectoral; they thus lie between the lowest of those from the corner of the 
mouth and the first which runs forward from the root of the pectoral, with which 
the furrow following most closely takes a quite strongly curved course. At the 
root of the pectoral fins both above and below are a number of short strongly 
curved furrows.” 
In the Newfoundland specimens the arrangement of ridges and furrows was 
the same, as will be seen on examining pls. 8 and 9. The number and course of 
the furrows are, however, subject to considerable variation. In some cases the fur- 
rows in the root of the mandible are continuous with those running forward from 
under the pectoral, and form one series with them. One or two pairs directly on 
the median line of the throat are shorter anteriorly than the lateral ones, so that 
there is quite a large plain area immediately under the tip of the mandible. 
The total number of furrows between the two pectorals varies considerably in 
different Newfoundland specimens, as follows: No. 1, about 80; No. 2, 62; No. 7, 
72; No. 18, 78; No. 4,56; No. 9, 62; No. 20, 76. ‘These totals were obtained by 
counting from the median line to the root of the pectoral on one side and multiply- 
ing by two. The average is the same as in Sars’s Lofoten Ids. specimen. 
The breadth of the ridges in the vicinity of the middle of their length in New- 
foundland specimens was 2 in. to 24 in., but at the posterior ends they increased 
in breadth to 4 inches. The breadth of the furrows depends chiefly on the pressure 
exerted from the interior of the body, though they do not always close together 
when this pressure is withdrawn. In the dead animal, the weight of the integu- 
ments which happen to be nearest the ground pulls the ridges which are higher up 
