CLASS ELASMOBItANCHII. 



89 



through the mouth, or, when this is occupied, through 

 the round openings along the sides, out of which it is 

 also allowed to escape. 



CLASS ELASMOBRANCHII (e las mo brang'kl I). 



The strap-gilled fishes have four or five pairs of long 

 gill openings. Their skeleton is cartilaginous, skin rough, 

 and the tail lobes are of unequal length (heterocercal) 

 (het er o ser'kal). It is in this class, we first meet with 

 animals having two pairs of appendages ; the anterior 

 (the pectoral) (pek'to rai), and the posterior (the pelvic) 

 (pel'vik). 



ORDER SQUALI (skwa'll). 



The Sharks are the butchers and scavengers of the 

 ocean. They follow ships pertinaciously, swallowing 

 greedily any thing thrown overboard.* Their teeth are 



FIG. 152. 



Sphf/r'na, zy ffce'nus. Hammer-headed Shark. ( 5 \;.) 



Shark's Teeth. 

 JV 7 ; Nasal orifice. 



* On slow-sailing merchant-ships, shark-fishing is a favorite pastime. A recent 

 account says : " I was holding the heavy hook and wire rope over the side, when 

 I felt that I had caught a big fish, and pulling it cautiously, a shark came to the 

 surface. I called out for help. He struggled so violently, lashing the water with 

 his tail and trying to bite the hook asunder, that we were obliged to keep dipping 



