BRITISH MAMMALS 
parts about the Orkneys and Shetlands, and less frequently the English 
and Irish shores. 
It has been known on several occasions to ascend rivers in England 
for some considerable distance, even as far up as Chelsea on the Thames, 
where three were seen in 1890. In character the Killer is fierce and 
rapacious, and has been likened to the wolf of the seas. They usually 
roam through the ocean in packs, travelling with great speed, and do 
not hesitate to attack large animals such as the Greenland Whale and 
Finner. Mr. E. W. Nelson, writing in the Rational Geographical 
Magazine, Washington, Nov. 19 16, p. 468, says : " Unlike most whales, 
the members of these schools do not travel in a straggling party, but 
swim side by side, their movements as regularly timed as those of soldiers. 
A regularly spaced row of advancing long black fins swiftly cutting the 
undulating surface of the sea produces a singularly sinister effect. 
" The evil impression is well justified, since Killers are the most savage 
and remorseless of whales." 
In attacking their quarry, if it be one of the larger Whales, the Killers 
approach it on both sides, and generally endeavour to tear out the tongue 
when the animal opens its mouth through exhaustion. 
Not only are whales and their young preyed upon by these fierce 
marauders, but other warm-blooded creatures, such as Seals and the young 
of the Walrus, also suffer. 
In the Northern Pacific great harm is done to the herds of the valuable 
fur seal when Killers get among them during migration. 
The Sperm Whale is safe from their attacks, as he is well able to defend 
himself with his powerful jaws. 
Some authorities have considered that there are several species of the 
genus Orca, but whether this is correct is at present uncertain. 
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