MARINE MAMMALS, AND FISHES 103 



In warm weather he rises to the surface, and has 

 the southern shark's habit of swimming with part 

 of the dorsal fin and tail above water. A timid 

 person, seeing this, would be extremely likely to get 

 on to dry land as speedily as possible. 



Two members of a family of large pelagic sharks 

 find their way into the North Sea, with greater, or 

 less frequency. One of these is known as the 

 porbeagle (Lamna cornubica), which seems to be 

 a corruption, or telescoping together of the words 

 porpoise, and beagle, or hunting-dog. He is bulky, 

 and thick set among the sharks, provided with 

 large sharp teeth, and quite capable of doing mis- 

 chief. Although he might not take the initiative 

 in an attack on man, he has the, character of being 

 ready to act on the defensive. An instance is 

 recorded by Day, of one which, when it found that 

 it was captured, made a spring at the fisherman, 

 and succeeded in making an ugly rent in his 

 clothes. 



The North Sea boasts another, perhaps more in- 

 teresting, certainly more peculiar member, of the 

 same family of large pelagic sharks. A thresher 

 (Alopecias vulpes) was ignominiously shovelled 

 into the trawl, off the Forth ; doubtless as he was 

 feeding on some fish at the bottom. Although 



