580 The Animal Kingdom 



The typical shark has the streamHned torpedo-Hke shape exempli- 

 fied by the dogfish. These animals are nearly all predaceous and are 

 rapid-swimming forms. Some of these are the largest fish found in the 

 ocean. One, the gigantic whale shark Rhincodon, may be up to 50 

 feet in length ; another, the basking shark, Cetorhinus, may be nearly as 

 big. The latter receives its name from its habits of browsing on plank- 

 ton near the ocean's surface. Both of these latter forms are essentially 

 planktonic feeders, and cannot be considered as dangerous species. The 

 great white shark, Carcharodon, which dwells in the coastal waters 

 of Australia has the reputation of attacking bathers and is much feared. 

 Most sharks, however, are not dangerous, but during accidents when 

 blood excites them, they may snap indiscriminately and thus inflict 

 damage. 



Fig. 195. — Some examples of the class Chondrichthyes. a, Pristis, the sawfish; 

 b, Sgualus, the dogfish shark; c, Sphyrna, the hammerhead shark; d, Cetorhinus, 

 the basking shark; e, Rhincodon, the whale shark; j", Carcharodon, the white shark; 

 (I, Manta, the Manta or devil ray; h, Dasyatis, the stingray; i, Torpedo, the electric 

 ray; J, Raja, the common ray; k, Chimaera, a chimaera. 



Quite unlike the sharks in general appearance are the rays which 

 are adapted for bottom dwelling. They are flattened forms and have 

 the gill slits ventral in position. Most of these are small in size, that 



