554 



The True Sharks 



of the head and at the base of the pectoral fin, and are capable 

 of Ijenumbing 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 Tctrouarcc occidentalis, the 

 crampfish of our Atlantic coast, black in color, and said some- 

 times to weigh 2 00 pounds. In California Tetronarce cali- 

 f arnica 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, 

 Narcobatns torpedo, the spiracles are fringed and the animal 

 is of smaller size. To A'arcine belong the smaller numbfish, 

 or " entemedor, " of tropical America. These have the spiracles 

 close behind the eyes, not at a distance as in Narcobatns and 

 Tetronarce. A'arciuc brasilioisis is found throughout the West 

 Indies, and Narcine entemedor in the Gulf of California. Astrapc, 

 a genus with but one dorsal fin, is common in southern Japan. 

 Fossil Xareobatiis and Astrapc occur in the Eocene, one speci- 

 men of the former nearly five feet long. A'ertebra^ of Astrape 

 occur in Prussia in the amber-beds. 



Petalodontidae. — Near the Squatinidcc, between the sharks 

 and the rays, Woodward places the large extinct family of 



Petalodontidcv, 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 Jatiassa and 

 Petalodus, widely distributed in 

 Carboniferous time. fanassa is 

 a broad fiat shark, or, perhaps, 

 a skate, covered with smooth 

 shagreen. The large pectoral fins 

 are grown to the head ; the rather 

 large ventral fins are separated from them. The tail is small 



Fig. .3-tG.— Teeth of Janassa lin- 

 gufcformis Attley. Carl:)oni('erous. 

 Family Petalodonlidaj. (After 

 Nicholson.) 



