FISHES, 543 
grade in temperature, a torpedo preserved its faculties during five or 
six hours; another, which remained during ten hours in 2 very small 
quantity of sea-water at a temperature of ro° 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 by 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 discharges, which demonstrates 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 ! 
The families of the sub-order Squalina are Scy//ide, or Dog-fishes ; 
Carcharide, or true Sharks ; Zygenide, or Hammerheaded Sharks ; 
Laminde; Galeide; Cestraciontide; Spinacide; and Sguatinide. 
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 Rays ; eyes lateral. 
Carcharide.—This family contains the true Sharks. Some species 
are said to attain the length of twenty and even thirty feet; but 
size is not their worst attribute; they have received, besides, 
strength and terrible teeth. Ferocious, voracious, impetuous, and 
insatiable, spread over almost every climate, inhabitants of every sea, 
and recently not seldom seen on our own shores, the sharks will 
rapidly pursue every fish, which fly at their approach; and threaten 
with their wide gullet the unfortunate victims of shipwreck, shutting 
them out from all hope of safety. 
The body of the shark is long, and its skin is studded with small 
tubercles: this skin becomes so hard, and takes so high a polish, 
that it is employed in the preparation of various ornamental work. 
This dense resisting coat protects the shark from the bites of every 
inhabitant of the sea, if there be any daring enough to approach it 
with that view. 
The back and sides of the White Shark, Carcharius vulgaris 
(Fig. 361), are of an ashy brown; beneath it is faded white. The 
head is flat, and terminates in a muzzle slightly rounded. Its terrible 
mouth is in the form of a semicircle, and of enormous size; the 
contour of the upper jaw of a shark of ten yards length being about 
two yards wide, and its throat being of a proportionate diameter to 
this monstrous opening. When the throat of the animal is open we 
see beyond the lips, which are straight and of the consistence of 
