— 
bo 
(or) 
THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 
BiGs 2: HIGHSe 
2 
uae ee LUGE, oh a 
FIG. 2. Fic. 6. 
/ 
Fic, 4. FIG, 7. 
DORSAL FIN OF BALZNOPTERA PHYSALUS (L.). AMERICAN AND EUROPEAN. 
Fic. 1.—SNooK’s ARM, NEWFOUNDLAND. AD. @. No. 24. Fic. 2,.—Snoox’s ARM, NEWFOUNDLAND. AD. 
@. No. 25. Fic. 3.—SNooK’s ARM, NEWFOUNDLAND. AD.¢. No. 23. FIG. 4.—GLOUCESTER, MaAss., IM. 2. 
(From DwicHt.) Fic. 5.—FINMARK, NoRWAY. Ap. (From MAM.) Fic. 6—BoRSELAER, NETHERLANDS. AD. 
$. (From VAN BENEDEN.) Fic. 7—LoroTen Ips., Norway. JR.¢ (FROM Sars.) 
PECTORAL FIN. 
The shape of the pectoral fin in the European B. physalus, according to Sars 
is “narrowly lanceolate, with the posterior angle often but little distinct.” This is 
true of the Newfoundland Finbacks. The anterior border is much straighter than 
in the Sulphurbottoms, and the distal half of the posterior margin, which is quite 
strongly concave in the latter, is straight in the Finback. These straight contours 
and the small size give the pectoral of the Finback a triangular appearance, quite 
different from that of the Sulphurbottom, as will be seen by comparing pl. 11, 
figs. 1, 2, and 4, and pl. 21. The shape of the pectoral of B. physalus is not 
as well shown in Sars’s figure (79, pl. 2) as in Delage’s photographs (32). In the 
former the anterior margin is too much curved, especially in the proximal half, and 
the posterior margin is too convex near the axilla. Much better are Sars’s litho- 
graphic figures of his Lofoten Ids. specimen (77, pl. 2, figs. 8 and 4), in which the 
triangular shape of the pectorals is admirably portrayed, though perhaps a little 
exaggerated. 
There is some variation in the relative length and width of the pectoral, as 
will be seen by consulting the table on p. 117, but it is not sufficient in any case to 
destroy the characteristic shape of the fin. 
In some Newfoundland specimens the contours are much more regular than 
in others, and in No. 17 there was a deep emargination at the tip anteriorly, due 
possibly to injury. In No. 3 the tip of the left pectoral was blunt and irregular, 
due to injuries. 
