The True Sharks 211 
of the head and at the base of the pectoral fin, and are capable 
of benumbing an enemy by means of a severe electric shock. 
The exercise of this power soon exhausts the animal, and a 
certain amount of rest is essential to recovery. 
The torpedoes, also known as crampfishes or numbfishes, 
are peculiarly soft to the touch and rather limp, the substance 
consisting largely of watery or fatty tissues. They are found 
in all warm seas. They are not often abundant, and as food 
they have not much value. 
Perhaps the largest species is Tetronarce occidentalis, the 
crampfish of our Atlantic coast, black in color, and said some- 
times to weigh 200 pounds. In California Tetronarce cali- 
fornica reaches a length of three feet and is very rarely taken, 
in warm sandy bays. Tetronarce nobiliana in Europe is much 
like these two American species. In the European species, 
Narcobatus torpedo, the spiracles are fringed and the animal 
is of smaller size. To Narcine belong the smaller numbfish, 
or “entemedor,”’ of tropical America. These have the spiracles 
close behind the eyes, not at a distance as in Narcobatus and 
Tetronarce. Narcine brasiliensis is found throughout the West 
Indies, and Narcine entemedor in the Gulf of California. Astrape, 
a genus with but one dorsal fin, is common in southern Japan. 
Fossil Narcobatus and Astrape occur in the Eocene, one speci- 
men of the former nearly five feet long. Vertebre of Astrape 
occur in Prussia in the amber-beds. 
Petalodontide.— Near the Squatinide, between the sharks 
and the rays, Woodward places the large extinct family of 
Petalodontide, with coarsely paved 
teeth each of which is elongate 
with a central ridge and one or 
more strong roots at base. The 
best-known genera are /anassa and 
Petalodus, widely distributed in 
Carboniferous time. /anassa is 
a broad flat shark, or, perhaps, 
Be a Adily Cotectrcne a skate, covered with smooth 
Family Petalodontide. (After shagreen. The large pectoral fins 
Nicholson.) 
are grown to the head; the rather 
large ventral fins are separated from them. The tail is small, 
