THE SHARKS AND RAYS 93 



Carchariidae 



The second great family of sharks represented in British 

 seas includes three of the commonest and one of the most 

 interesting. The sharks of this family are distinguished by 

 the presence of the nictitant membrane. Spiracles are not 

 a constant character, for they are present in the smooth-hound 

 and tope, but absent in the blue shark and hammerhead. 

 Equally varying is the presence of a small pit on the back, 

 just before the tail fin, for we find this in the hammerhead and 

 blue shark, but not in the tope and smooth-hound. None 

 of these sharks have spines in front of the dorsal fins, such 

 as we shall find present in one important family with five 

 British representatives ; and their teeth are, as a rule, serrated 

 in examples of moderate size, though not necessarily in either 

 very young or very old individuals. 



The Blue Shark {Carcharias glaucus) is a graceful and 

 beautiful fish, though it unavoidably shares the prejudices 

 against its order, and the fishermen would unanimously vote 

 it ugly. With them it is a case of " handsome is as hand- 

 some does," and the blue shark certainly tears their nets 

 and robs their lines more than most. It has the typical form 

 of sharks, with its long pointed snout and five gill-openings, 

 and the entire back and sides are of a deep blue, shading off 

 to white below. 



As already mentioned, it has no spiracles, and there is a 

 small pit at the base of the tail, while the teeth of medium- 

 sized examples are saw-edged, a character that is apparently 

 not acquired until middle age and is subsequently dropped. 



Only those who fish down in Cornwall can have many 

 opportunities of watching the active movements of the blue 

 shark in pursuit of its prey, showing an activity that we look 

 for in vain in the prowling porbeagle ; and the angler who, 

 fortunately or otherwise, according to his aspirations, hooks 

 one on the rod has further occasion to admire the free and 



