262 



THE SHARK. 



seem calculated to try the strength of their di- 

 gestive powers. It does not appear that their 

 sense of smell always guides them in procuring 

 food, as paper, canvas, or indeed any thing 

 thrown overboard which they are capable of 

 swallowing, is greedily devoured by them. To 

 decide correctly on the habitat, or extent of 

 range, taken by any particular species, is diffi- 

 cult, and requires a numerous collection of facts. 

 Frequent mistakes are made in this respect ; as 

 in tlie instance of the Squalus cornuhicus, or 

 porbeagle shark, whose habitat was supposed 

 to be confined to the British coasts, but which I 

 have since discovered has been found, although 

 rarely, inhabiting the coasts of New Zealand. 



The teeth of sharks vary in different species. 

 Blumenbach observes, that '' in most of the 

 sharks the mouth is furnished with very nume- 

 rous teeth, for the supply of such as may be lost. 

 The white shark has more than two hundred, 

 lying on each other in rows, almost like the 

 leaves of an artichoke. Those only which form 

 the front row have a perpendicular direction, 

 and are completely uncovered. Those of the 

 subsequent rows are, on the contrary, smaller, 

 have their points turned backwards, and are 

 covered by a kind of gum. These come through 

 the covering substance, and pass forward, when 



