CLASS ELASMOBRANCHII 



429 



Crustacea. The great white shark, Carcharodon carcharias, 

 occurs in all warm seas. It reaches a length of over thirty feet 

 and has earned the name of man-eater by occasionally devouring 

 a human being. One of the most peculiar sharks is the hammer- 



Fig. 363. — -Hammerhead shark, Sphyrna tudes. af., anal fin; c.f, caudal 

 fin; cl, clasper; e, eye. (From Lankester's Treatise, after Day.) 



head, Sphyrna tudes (Fig. 363), which is also found in warm seas. 

 Its head is shaped like the head of a mallet, with an eye (e) at 

 either end. 



Order 2. Raji. — Rays or Skates. — The rays or skates are 

 flattened dorso-ventrally and adapted for living on the bottom. 



Fig. 364. — Sawfish, Pristis peclinatus. A, side view. B, ventral view. 

 (From Dean; A, after Goode.) 



Some of them are only slightly flattened, whereas others are 

 broader than long. The sawfish, Pristis peclinatus (Fig. 364), 

 lives in tropical seas and is abundant in the Gulf of Mexico. 

 It reaches a length of from ten to twenty feet. The saw of 

 a large specimen is about five feet long; it is used as a 



