THE SHARKS AND RAYS 85 



well informed that " true " sharks, whatever the qualification 

 may signify, are met with only in tropical seas, and are 

 consequently absent from our own. While, beyond a doubt, 

 both the sharks and rays find their highest development in the 

 warmer seas of the globe, where their scavenging work is in 

 greatest demand, it is also a fact that such immense or 

 specialised kinds as the Greenland shark {^Liemargui) and 

 starry ray {Raid) abound in arctic seas. In British waters, 

 too, there is a large number of both sharks and rays, and 

 although popular consent has called the smaller sharks by the 

 name of " dog-fish," there is no scientific line of demarcation 

 between the two even in the matter of size, for some of the 

 so-called "dog-fishes" grow to a larger size than some of 

 the " true " sharks. 



THE SHARKS {Selachoidei) 



Our British sharks are seventeen in number, the latest 

 addition being Centrophorus squamosus, a relative of the spur- 

 dog long known on the coast of Portugal, but added to the 

 British fauna by the Irish Survey of 1891, a single specimen 

 of 4^ in. having been caught on a long line off the Mayo 

 coast in 250 fathoms. The species is very fully described by 

 Holt and Calderwood in the 'Transactions of the T^oyal Dublin 

 Society for September, 1895. 



The British sharks fall under six families, and of these it 

 will be convenient to give a list before passing to some brief 

 notes on each kind. 



Sharks have no great commercial value on our coasts, 

 though elsewhere, and particularly in the East, portions of 

 them are highly appreciated as food. The smaller dog-fishes, 

 on the other hand, find a ready market to-day at Brighton 

 and elsewhere on the South Coast, where, twenty years ago 

 they would have been thrown away as offal. 



