554 The True Sharks 



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. Vertebrae of Astrape 

 occur in Prussia in the amber-beds. 



Petalodontidae. Near the Squatinida, between the sharks 

 and the rays, Woodward places the large extinct family of 



Petalodontida, 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 Janassa and 

 Petalodus, widely distributed in 

 Carboniferous time. Janassa is 

 a broad flat shark, or, perhaps, 

 a skate, covered with smooth 

 ly Petalodontida. (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, 



