KtTNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 40. N:0 5. Ii!) 



be that the dorsal fin of the northern Humpback generally has a position which 

 represents an ontogenetically earlier stage in the development of the southern race. 



The length of the pectoral fin is in tbe semi-adult 31,, % of the total length, 

 and in the foetuses resp. 31, s % and 28, s %. AU these measurements fall within 

 the range of variation of the northern Humpback, aecording to True's (20) tables. 



The flukes are usually c ut off before the whales are tugged in to the factory. 

 Sörling had therefore only opportunity to measure the flukes of the foetuses. These 

 are, of course, comparatively not fully as large^as those of the adult animals. Their 

 breadth from tip to tip expressed in percentage of the total length of the foetuses 

 is resp. 29, 6 and 29, 2 . Aecording to True (20) the same percentage in the adult 

 northern Humpback varies from 30 to 38,-. but in one american specimen sinks so 

 low as to 27,i. There is thus a very considerable amount of variation with regard 

 to this organ. 



When Sörling first arrived at South Georgia, in the middle of Nov. 1904, the 

 Humpbacks were very numerous off the coast and continued to be so to about the 

 middle of May 1905. Between the first of June, however, and the first of Oct. that 

 year none was seen or shot. It is thus evident that the Humpback migrates from 

 South Georgia somewhere and stays away during the winter. 



The Humpbacks frequented especially the »bank» some 30 — 35 miles off the 

 coast. They are gregarious and appear in small schools swimming back and forth. 

 The Humpback shows a certain degree of curiosity and it often approaches the fatal 

 whaling steamer as if to see wha% it is. In some places the Humpbacks appeared 

 to be very numerous, so that their spouts were seen everywhere, all round the vessel. 

 Sörling says, »the spouts rose all round us so that the sea could be compared with 

 a field on which buslies grew. » 



When the southern atlantic Humpback lies quiet at the surface it shows, aecord- 

 ing to Sörling, the protuberance around the blow-hole and the anterior portion of 

 the back above the water, but not the dorsal fin. 



Racovitza has published a photo in which the protuberance round the blow- 

 hole and the dorsal fin, but not the intermediate portion of the back, are visible, 

 it is thus apparent that such a position as well is possible in the Humpback to the 

 west of Graham land. 



When this species sounds it always shows the flukes, even if it only makes a 

 short dive. 



It stays below for 10 — 15 to 30 minutes. 



Its spout is not very high. Sörling calls it »broom-shaped* in his notes. It 

 is not by far so high as that of the Finbacks. 



Of the 75 Humpbacks caught, only three were pregnant females. The first of 

 these was shot the 28th of Febr. and its foetus (Pl. VI fig. 27) measured 1,;.-. m. in 

 length. About two weeks låter the second was shot, and its foetus measured only 

 1,23 m. in length. The third was shot some weeks låter, but its foetus was not 

 measured as it was spoiled before Sörling heard about it. 



Although these notes are somewhat scanty it may be concluded from them 



