SEALS AND WHALES OF THE BRLTISH SEAS. 



PORPOISE. 



The Common Porpoise {PJiocoena comtmmis, F. Cuv. ; Delphimis phocosna, 

 Linn.) is the best known of the Cetacea inhabiting the North Sea, being met 

 with in abundance all round the British Isles, seldom occurring far from land, 

 and often ascending large rivers for a considerable distance : it has been seen in 

 the Thames as high as London Bridge. 



Nothing can be more interesting than to watch a shoal of these animals 

 at sea, sometimes tumbling and gambolling under the bows of the vessel 

 which is passing rapidly through the water., with as much ease as if she 

 were motionless, or chasing each other playfully round and round the 

 ship as she lies becalmed, their white bellies glistening in the clear 

 sea, and frequently, apparently out of pure mad delight, leaping completely 

 out of the water, returning to their native element with a most determined 

 header. But it is not till seen in the glass-sided tank of the aquarium that 

 the beauty, and even poetry of motion of these animals can be fully appreci- 

 ated ; swimming along in a series of gentle curves, they just bring the blow- 

 hole to the surface, breathe without stopping, and continue the curve, till in 

 due course they reach the surface again. This is repeated for the whole 

 length of their spacious tank, or is varied by unexpected eccentricities, all 

 indescribably graceful. Under these favourable circumstances for observation 

 it is also clearly seen that the horizontal tail is the propeller which gives the 

 motion ; the alternate upward and downward pressure of this organ against 

 the water evidently producing the graceful mode of progression which is so 

 difficult to describe, but so easily understood when witnessed. The flippers 

 are not used as propellers. When the animal is moving forwards they are 

 laid back, against the body ; but when it wishes to stop, they are stretched 



