228 THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



evidently concave posterior border. The tip, which is rather obtuse, is strongly 

 bent backward, so that the whole fin shows a considerable resemblance to that of 

 the Vaagehval \Balcenoptera dcnto-rostrata]." 



From the foregoing discussion it would appear that there is no constant differ- 

 ence between the Newfoundland, Greenland, and European Humpbacks as regards 

 the shape of the dorsal fin, unless it be that in the Greenland animal, or KeporJcak, 

 the tip is thicker. As in the Finbacks, the shape of the dorsal appears to vary to 

 a large extent in different individuals. 



Hallas figured the dorsal of an Iceland Humpback (60, 173) as sloping and 

 convex or straight posteriorly, much as in Eschricht's Greenland Keporkak. 



The different American and European specimens show a remarkable uniformity 

 in the height of the fin, which varies only between 1.9 % and 2.5 % of the total length 

 of the body. As regards its position, there is, on the other hand, a lack of uni- 

 formity. After making due allowance for difference in manner of taking measure- 

 ments, etc., it still appears probable that the fin is not always situated at exactly 

 the same relative distance from the head. No two observers agree as to the length 

 of the base of the fin. This is because the margins pass by imperceptible gradations 

 into the general contour of the back. 



Rawitz (74, 82) repudiates the idea that the dorsal resembles a bunch, and 

 states that in the Bear Id. specimens which he examined the fin had a strongly 

 convex anterior border bent backward, and the posterior border concave forward. 

 He asserts that the white color on the dorsal of the Greenland Keporledk described 

 by Eschricht was probably due to post-mortem changes because his four Bear Id. 

 specimens had entirely black dorsals. It is a fact, however, that the Newfound- 

 land specimens had white marks on the dorsal fin. 



THE PECTORAL FIN. 



The form of the pectoral is one of the most peculiar characters of the Hump- 

 back, while in length it exceeds the pectorals of all other whales. The fin is 

 long, narrow, and thin. On the anterior (upper, or radial) margin it presents 

 a number of protuberances, which together with the emarginations between them, 

 produce a serrated outline. There are similar protuberances on the posterior (or 

 ulnar) margin, especially at the distal end, but less in number, and much less promi- 

 nent. In the foetus the protuberances are all very strongly marked, and are made 

 more striking (in Newfoundland specimens) on account of their being lighter in 

 color than the general surface of the fin. In shape and texture they remind one not 

 a little of the tubercles on the head. 



Eschricht (37, 79) and Struthers (89, 5) by their descriptions and figures have 

 made plain the connection of the anterior protuberances with the internal structure 

 of the fin. Each protuberance marks the position of a cartilage of the manus. 



The two largest, namely, the one at the proximal end of the series, and one 

 about midway, mark the position, respectively, of the distal epiphysis of the radius, 

 and the terminal cartilage of the anterior (2d) digit. The protuberances between 

 these larger ones mark the position of the intermediate cartilages of the 2d digit, 

 while those beyond mark the position of the cartilages of the 3d digit. 



