CARTILAGINOUS FISHES. 517 



a yard in height by a third of that in diameter, and at 22 Centi- 

 grade in temperature, a torpedo preserved its faculties during five 

 or six hours ; another, which remained during ten hours in a very 

 small quantity of sea- water at a temperature of 10 to 11 Cent., 

 and which seemed dead, revived a little when placed in water 

 at 20 Cent., and gave shocks during an hour. If held firmly 

 hy the tail, and pressed both above and below by a platinum rod 

 to gather the true electricity, the animal contracts itself violently ; 

 but its movements are not always accompanied by electrical dis- 

 charges, which demonstrate that the jets of electrical matter are not 

 the result simply of the muscular contractions, but that they are 

 subject to the will of the animal, and evidently given for resisting its 

 enemies, and benumbing its prey. How wonderful and varied are 

 the resources which Nature grants to her creatures in order to secure 

 their existence ! 



SQUALID^:. 



This family approaches more to the Eaias than any other fish ; but 

 all the species have a lengthened body, merging into a thick tail, 

 pectorals moderate in size, gill-openings on the sides of the neck, 

 and not beneath the body, as in the Kaia ; eyes lateral ; and the rough- 

 ness of their skin is a protection from their enemies. The family 

 comprehends the Sharks, Dogfishes, Hammerheads, and Saw -fish. 



Fig. 352. The Shark (Uarcharius vulgari-s). 



The sharks are said to attain the length of twenty and even thirty 

 feet ; but its size is not its worst attribute. It has received, besides, 

 strength and terrible arms. Ferocious, voracious, impetuous, and in- 



