378 POLAR PROBLEMS 



casionally to the South Shetlands. In nearly all parts of its old range 

 the fur seal has been exterminated. 



The American southern sea lion (Otaria byronia) is found only 

 north of the zone of floating ice and nowhere at a great distance from 

 the coasts of South America. Together with many other Magellanic 

 marine organisms it ranges northward in the Humboldt Current region 

 to Cape Blanco, Peru (4° 16' S.). A related sea lion occupies a cor- 

 responding area, outside the extreme limit of floating bergs, at islands 

 south of New Zealand. The distribution of the species and genera 

 exhibits nothing approaching bipolarity. The present representatives 

 of southern pinnipeds in the northern hemisphere, such as a sea 

 elephant, and a fur seal not of the Alaskan genus, on the west coast 

 of North America, have evidently pierced the warm-water barrier 

 at points vulnerable because of current conditions. Or, as is not 

 out of the question, the transequatorial migration may have originally 

 proceeded in the opposite direction. Far more must be learned of the 

 history of the several groups, and far more of the factors which still 

 so rigidly control distribution, before such problems can be solved. 



Antarctic and Sub -Antarctic Cetaceans 



There remain among vertebrates only the whales and smaller 

 cetaceans which probably exist in greater abundance in the rich 

 southern waters than anywhere else, but about whose life history and 

 seasonal movements all too little is yet known. One or more genera 

 of the lesser whales are perhaps endemic. The majority of the larger 

 cetaceans are types identical with, or closely related to, species 

 of world-wide distribution, which reduces their zoogeographic value. 

 The tradition of plentiful right whales (Balaena) in Antarctic seas 

 is apparently traceable to erroneous identification by Sir James 

 Clark Ross. Sperm whales (Physeter) likewise tend to avoid the 

 colder waters, and examples have been captured only rarely by whaling 

 steamers from the stations at South Georgia. But humpback whales 

 (Megaptera) , several species of fin whales (Balaenoptera) , and killers 

 (Orca) are found in numbers which apparently increase with the 

 latitude to the very foot of the Great Barrier. Shoals of destructive 

 killer whales remain throughout the year as far south as open water 

 can be found; indeed these creatures sometimes break up heavy sea 

 ice with the apparent object of precipitating their prey into the water. 

 Crab-eater seals are said to be the most frequent victims owing to 

 their liking for the pack ice, while the Weddell seals, as noted hereto- 

 fore, are protected by their shore-haunting proclivities. 



Unfortunately, human concern with the great southern cetaceans, 

 such as the humpback, finback, and blue whale, has been chiefly com- 

 mercial. After the exhaustion of many whaling grounds in the 



