10 SHARKS. 



dition. A number of vascular fibres are provided, which hang 

 from the orifices of the breathing holes, and even from the 

 temjioral orifices where these are provided; and they do not 

 disappear until the creature is j^repared for its permanent state 

 of existence. It is a remarkable instance of the accuracy with 

 which the transitory condition of interuterine existence is pro- 

 vided for, that the whole of the contents of the nutrient bag 

 forming the egg has become absorbed into the body at the very 

 instant when its presence is no longer required, and the fish 

 has become capable of seeking for its own support. 



It may be mentioned as a piece of superstition, that in no 

 very distant times the teeth of Sharks, under the name of ser- 

 pent's teeth, were set in silver, and used to render more easy 

 the cuttinsT of the teeth in children. It was more in reference 

 to their supposed ocult virtue, than to their mechanic effect, 

 that even so wise a man as the physician and naturalist Rondele- 

 tius believed that when reduced to powder they formed also 

 an excellent tooth powder. 



SHARKS. 



These are fishes of a lengthened form, having the mouth 

 and nostrils placed under a projecting snout, the jaws furnished 

 with several rows of teeth, the gill-covers bound down to the 

 side, and the openings like separate slits in the skin, not less 

 than five in number. The fins covered with the common skin, 

 the tail irregularly lobed, the upper portion being of greater 

 length than the lower, and having the vertebrae, or joints of 

 the back, carried onward close to the border of the caudal fin. 



There are some kindred species, which vary in some degree 

 from the shape most common in this family, by approaching 

 more nearly to that of the Hays; on which account they are 

 said to be aberrant. Of these we shall take notice when 

 describing such of them as have been taken on the British 

 coasts. 



The following arrangement of such of the genera of this family 

 as belong to the catalogue of British fishes, is derived from the 

 "Animal Kingdom" of the Baron Cuvier, but modified in a 

 few particulars, by the observations of the German naturalists 

 Muller and Henle, and by Dr. Gray. 



