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CETACEANS. 
frequently one or more rows of horny tubercles on the front edge of the back-fin, 
or of the ridge which takes its place. 
common The common porpoise is by far the best-known of all the Cetaceans 
Porpoise. frequenting the British coasts, generally keeping near the shores, and 
often ascending the larger rivers to considerable distances. It is characterised by 
having twenty-five to twenty-six teeth on each side of the jaws, by the sloping head, 
the equality in the length of the upper and lower jaws, and by the length of the 
mouth exceeding half that of the flipper. There is a large fin on the back, which is 
triangular in shape, and situated somewhat in advance of the middle of the total 
the common PORPOISE (A nat. size). 
Distribution. 
length of the animal. In length, the common porpoise measures about 5 feet, or 
rather more. The colour of the upper-parts is dark slate, or blackish, while the 
sides become gradually lighter till the colour fades into the pure white of the under¬ 
parts. In some cases there is a yellowish or pinkish tinge on the flukes. 
The distribution of this species is extensive, comprising the North 
Atlantic and North Pacific Oceans, the North Sea, and the coasts of 
Europe. In Davis Strait it extends as far northwards as latitude 67° or 69°, and 
it also occurs on the Alaskan coasts; while southwards it extends in America to the 
shores of New Jersey and Mexico. In the Mediterranean it is comparatively rare. 
Porpoises associate in shoals or herds of considerable size; and 
their sportive gambols are probably familiar to most of our readers. 
Habits. 
